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Note: This page contains sample records for the topic "quantum dot tracers" from the National Library of EnergyBeta (NLEBeta).
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1

Quantum Dots Executive Overview  

E-Print Network (OSTI)

Quantum Dot Sol-Gel Nanocomposites (patent pending) n Nanocrystal Quantum Dot Light Emitting Diode (patent (CRADA) Business Opportunities LANL's quantum dot portfolio includes a high-efficiency light emitting diode (LED) design based on non-radiative energy transfer from a quantum well into a layer of colloidal

2

Success Stories: Quantum Dots  

NLE Websites -- All DOE Office Websites (Extended Search)

Quantum Dots Outshine the Competition for Biomedical Assays Quantum Dots Outshine the Competition for Biomedical Assays Quantum Dots (Qdots), nano-scale semiconductor crystals that emit a range of bright colors when excited by a light source such as a laser, are shining brightly these days. The Berkeley Lab developed technology has been licensed by Quantum Dot Corporation and is being used as fluorescence probes for biomedical assays. The technology just won an R & D 100 Award and Quantum Dot Corporation was named by Fortune magazine as one of 2004's "Cool Companies." Science honored the technology as one of the Top 10 Breakthroughs of the Year in 2003, and Nanotechnology Now named Quantum Dots as the Best Nanotech Product in 2003, among other honors. Quantum Dot Corporation (QDC) is a 1998 start-up biotechnology company

3

Quantum Dots: Theory  

SciTech Connect

This review covers the description of the methodologies typically used for the calculation of the electronic structure of self-assembled and colloidal quantum dots. These are illustrated by the results of their application to a selected set of physical effects in quantum dots.

Vukmirovic, Nenad; Wang, Lin-Wang

2009-11-10T23:59:59.000Z

4

Quantum Dot Fluorescence Lifetime Engineering with DNA ...  

Science Conference Proceedings (OSTI)

Quantum Dot Fluorescence Lifetime Engineering with DNA Origami ... such as metal nanoparticles and semiconductor quantum dots – is challenging ...

5

A quantum dot heterojunction photodetector  

E-Print Network (OSTI)

This thesis presents a new device architecture for photodetectors utilizing colloidally grown quantum dots as the principle photo-active component. We implement a thin film of cadmium selenide (CdSe) quantum dot sensitizers, ...

Arango, Alexi Cosmos, 1975-

2005-01-01T23:59:59.000Z

6

Thick-Shell Nanocrystal Quantum Dots  

NLE Websites -- All DOE Office Websites (Extended Search)

Thick-Shell Nanocrystal Quantum Dots Thick-Shell Nanocrystal Quantum Dots Colloidal nanocrystal quantum dots comprising an inner core having an average diameter of at least 1.5 nm...

7

Nontoxic quantum dot research improves solar cells  

NLE Websites -- All DOE Office Websites (Extended Search)

Nontoxic quantum dot research improves solar cells Nontoxic quantum dot research improves solar cells Solar cells made with low-cost, nontoxic copper-based quantum dots can achieve...

8

Quantum Dot Solar Cells: Preprint  

DOE Green Energy (OSTI)

Presented at the 2001 NCPV Program Review Meeting: Potential of quantum dot solar cells to increase the maximum attainable thermodynamic conversion efficiency of solar photoconversion to about 66%.

Nozik, A. J.

2001-10-01T23:59:59.000Z

9

Spintronics with Si quantum dots  

Science Conference Proceedings (OSTI)

Electron transport through small Si quantum dot is investigated. The B-dependence of energy levels is dominated by the Zeeman shift, allowing us to measure the spin difference between two successive ground states directly. Combined with the ability ... Keywords: Coulomb blockade, Si nanostructures, quantum dots, spin blockade

Leonid P. Rokhinson; Lingue J. Guo; Steven Y. Chou; Daniel C. Tsui

2002-08-01T23:59:59.000Z

10

2009 Bronze Medal for Quantum Dot Metrology  

Science Conference Proceedings (OSTI)

... Citation: The team is recognized for their scientific and engineering achievements in semiconductor quantum dot metrology. ...

2011-10-24T23:59:59.000Z

11

Quantum Dots Jeff Harbold, Monica Plisch  

E-Print Network (OSTI)

Quantum Dots Jeff Harbold, Monica Plisch I. Introduction Quantum dots are semiconductor to control size. Quantum dots are a subject of intense research at Cornell and other institutions. The figure below shows STEM images of quantum dots taken in the Silcox lab at Cornell. Left: low resolution STEM

Gaeta, Alexander L.

12

JILA Solves Problem of Quantum Dot 'Blinking'  

Science Conference Proceedings (OSTI)

... quantum dots used in the JILA experiments were made of cadmium-selenide cores just 4 nanometers wide coated with zinc sulfide. When a dot is ...

2012-03-05T23:59:59.000Z

13

Microwave Synthesis Connects With the (Quantum) Dots  

Science Conference Proceedings (OSTI)

... Making good quantum dots for biological research is complex. ... serves as a tether to attach additional functional molecules that cause the dot to bind ...

2012-10-18T23:59:59.000Z

14

Thick-Shell Nanocrystal Quantum Dots  

NLE Websites -- All DOE Office Websites (Extended Search)

Thick-Shell Nanocrystal Quantum Dots Thick-Shell Nanocrystal Quantum Dots Thick-Shell Nanocrystal Quantum Dots Colloidal nanocrystal quantum dots comprising an inner core having an average diameter of at least 1.5 nm and an outer shell, where said outer shell comprises multiple monolayers, wherein at least 30% of the quantum dots have an on-time fraction of 0.80 or greater under continuous excitation conditions for a period of time of at least 10 minutes. Available for thumbnail of Feynman Center (505) 665-9090 Email Thick-Shell Nanocrystal Quantum Dots Colloidal nanocrystal quantum dots comprising an inner core having an average diameter of at least 1.5 nm and an outer shell, where said outer shell comprises multiple monolayers, wherein at least 30% of the quantum dots have an on-time fraction of 0.80 or greater under continuous

15

All inorganic colloidal quantum dot LEDs  

E-Print Network (OSTI)

This thesis presents the first colloidal quantum dot light emitting devices (QD-LEDs) with metal oxide charge transport layers. Colloidally synthesized quantum dots (QDs) have shown promise as the active material in ...

Wood, Vanessa Claire

2007-01-01T23:59:59.000Z

16

CNM Highlight: Quantum Dot-Induced Transparency  

NLE Websites -- All DOE Office Websites (Extended Search)

Quantum Dot-Induced Transparency Quantum Dot-Induced Transparency Using rigorous and realistic numerical simulations, staff in the Nanophotonics and Theory and Modeling groups have recently demonstrated that a single semiconductor nanocrystal, or quantum dot, can cancel the scattering and absorption by a much larger metal nanostructure. Placing a quantum dot near a metal is known to strongly modify the rate at which the dot emits light. If the interaction between the dot and the metal is strong enough, scattering and absorption by the metal can be nearly eliminated at the quantum-dot resonance frequency, according to the simulations. This occurs even though the dot by itself simply absorbs light, and even though this absorption is nearly 100,000 times smaller than absorption by the metal nanostructure.

17

Quantum Dot Light Emitting Diode  

SciTech Connect

The project objective is to create low cost coatable inorganic light emitting diodes, composed of quantum dot emitters and inorganic nanoparticles, which have the potential for efficiencies equivalent to that of LEDs and OLEDs and lifetime, brightness, and environmental stability between that of LEDs and OLEDs. At the end of the project the Recipient shall gain an understanding of the device physics and properties of Quantum-Dot LEDs (QD-LEDs), have reliable and accurate nanocrystal synthesis routines, and have formed green-yellow emitting QD-LEDs with a device efficiency greater than 3 lumens/W, a brightness greater than 400 cd/m{sup 2}, and a device operational lifetime of more than 1000 hours. Thus the aim of the project is to break the current cost-efficiency paradigm by creating novel low cost inorganic LEDs composed of inorganic nanoparticles.

Kahen, Keith

2008-07-31T23:59:59.000Z

18

Quantum Dot Light Emitting Diode  

SciTech Connect

The project objective is to create low cost coatable inorganic light emitting diodes, composed of quantum dot emitters and inorganic nanoparticles, which have the potential for efficiencies equivalent to that of LEDs and OLEDs and lifetime, brightness, and environmental stability between that of LEDs and OLEDs. At the end of the project the Recipient shall gain an understanding of the device physics and properties of Quantum-Dot LEDs (QD-LEDs), have reliable and accurate nanocrystal synthesis routines, and have formed green-yellow emitting QD-LEDs with a device efficiency greater than 3 lumens/W, a brightness greater than 400 cd/m2, and a device operational lifetime of more than 1000 hours. Thus the aim of the project is to break the current cost-efficiency paradigm by creating novel low cost inorganic LEDs composed of inorganic nanoparticles.

Keith Kahen

2008-07-31T23:59:59.000Z

19

Quantum Dot Production Method - Available Technologies - PNNL  

Summary. This is a method of producing quantum dot materials involving deposition of a metal on an oxide substrate in an oxidizing environment to form ...

20

Etched Quantum Dots Shape Up as Single Photon Emitters ...  

Science Conference Proceedings (OSTI)

Etched Quantum Dots Shape Up as Single ... of quantum dot can be shaped and positioned ... somewhat haphazard process results in irregular shapes. ...

2011-10-14T23:59:59.000Z

Note: This page contains sample records for the topic "quantum dot tracers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

NREL Certifies First All-Quantum-Dot Photovoltaic Cell; Demonstrates...  

NLE Websites -- All DOE Office Websites (Extended Search)

Renewable Energy Laboratory (NREL) have certified the first all-quantum-dot photovoltaic cell, which was based on lead sulfide and demonstrated reasonable quantum dot solar...

22

New Quantum Dot Technique Combines Best of Optical and ...  

Science Conference Proceedings (OSTI)

New Quantum Dot Technique Combines Best of Optical and Electron ... over a sample that has been coated with specially engineered quantum dots. ...

2013-06-25T23:59:59.000Z

23

Thick-shell nanocrystal quantum dots  

DOE Patents (OSTI)

Colloidal nanocrystal quantum dots comprising an inner core having an average diameter of at least 1.5 nm and an outer shell, where said outer shell comprises multiple monolayers, wherein at least 30% of the quantum dots have an on-time fraction of 0.80 or greater under continuous excitation conditions for a period of time of at least 10 minutes.

Hollingsworth, Jennifer A. (Los Alamos, NM); Chen, Yongfen (Eugene, OR); Klimov, Victor I. (Los Alamos, NM); Htoon, Han (Los Alamos, NM); Vela, Javier (Los Alamos, NM)

2011-05-03T23:59:59.000Z

24

Quantum Optics: Colloidal Fluorescent Semiconductor Nanocrystals (Quantum Dots)  

E-Print Network (OSTI)

U ncorrected Proof Chapter 3 Quantum Optics: Colloidal Fluorescent Semiconductor Nanocrystals (Quantum Dots) in Single-Molecule Detection and Imaging Laurent A. Bentolila, Xavier Michalet, and Shimon quantum dots (QDs), have emerged as new powerful fluorescent probes for in vitro and in vivo biological

Michalet, Xavier

25

Biocompatible Quantum Dots for Biological Applications  

Science Conference Proceedings (OSTI)

Semiconductor quantum dots are quickly becoming a critical diagnostic tool for discerning cellular function at the molecular level. Their high brightness, long-lasting, size-tunable, and narrow luminescence set them apart from conventional fluorescence dyes. Quantum dots are being developed for a variety of biologically oriented applications, including fluorescent assays for drug discovery, disease detection, single protein tracking, and intracellular reporting. This review introduces the science behind quantum dots and describes how they are made biologically compatible. Several applications are also included, illustrating strategies toward target specificity, and are followed by a discussion on the limitations of quantum dot approaches. The article is concluded with a look at the future direction of quantum dots.

Rosenthal, Sandra [ORNL; Chang, Jerry [Vanderbilt University; Kovtun, Oleg [Department of Chemistry, Vanderbilt University, 7300 Stevenson Ctr Ln, Nashville, TN 37235, USA.; McBride, James [Vanderbilt University; Tomlinson, Ian [Oak Ridge National Laboratory (ORNL)

2011-01-01T23:59:59.000Z

26

Multiple Vertically Stacked Quantum Dots, Quantum Wires and ...  

Science Conference Proceedings (OSTI)

On the other hand, it is proposed that the presence of quantum dots in the InGaN active region result in high external quantum efficiency despite the high ...

27

Semiconductor Quantum Dots and Quantum Dot Arrays and Applications of Multiple Exciton Generation to Third-Generation Photovoltaic Solar Cells  

E-Print Network (OSTI)

to Third-Generation Photovoltaic Solar Cells A. J. Nozik,*,, M. C. Beard, J. M. Luther, M. Law,§ R. J. Applications: Quantum Dot Solar Cells 6884 6.1. Quantum Dot Solar Cell Configurations 6885 6.1.1. Photoelectrodes Composed of Quantum Dot Arrays 6885 6.1.2. Quantum Dot-Sensitized Nanocrystalline TiO2 Solar Cells

George, Steven C.

28

The confinement energy of quantum dots  

E-Print Network (OSTI)

One of the most significant research interests in the field of electronics is that on quantum dot, because such materials have electronic properties intermediate between those of bulk semiconductors and those of discrete molecules. Confinement energy is a very important property of quantum dot. In this study, quantum confinement energy of a quantum dot is concluded to be h2/8md2 (d being the diameter of the confinement) and not h2/8ma2 (a being the radius of the confinement), as reported in the available literature. This is in the light of a recent study [1]. This finding should have a significant impact in the understanding of the physics of quantum dot and its technological application.

Samrat Dey; Devkant Swargiary; kishan Chakraborty; Debasmita Dasgupta; Darsana Bordoloi; Rituja Saikia; Darsana Neog; Shishila Shimray; Supriyanka Paul; Kabita Brahma; Joydeep Dey; Saurav Choudhury

2012-12-11T23:59:59.000Z

29

Theory Of Alkyl Terminated Silicon Quantum Dots  

DOE Green Energy (OSTI)

We have carried out a series of ab-initio calculations to investigate changes in the optical properties of Si quantum dots as a function of surface passivation. In particular, we have compared hydrogen passivated dots with those having alkyl groups at the surface. We find that, while on clusters with reconstructed surfaces a complete alkyl passivation is possible, steric repulsion prevents full passivation of Si dots with unreconstructed surfaces. In addition, our calculations show that steric repulsion may have a dominant effect in determining the surface structure, and eventually the stability of alkyl passivated clusters, with results dependent on the length of the carbon chain. Alkyl passivation weakly affects optical gaps of silicon quantum dots, while it substantially decreases ionization potentials and electron affinities and affect their excited state properties. On the basis of our results we propose that alkyl terminated quantum dots may be size selected taking advantage of the change in ionization potential as a function of the cluster size.

Reboredo, F; Galli, G

2004-08-19T23:59:59.000Z

30

Photodetectors based on colloidal quantum dots  

E-Print Network (OSTI)

Inspired by recent work demonstrating photocurrent enhancement in quantum-dot (QD) solids via post-deposition chemical annealing and by recent successes incorporating single monolayers of QDs in light-emitting devices ...

Oertel, David C. (David Charles)

2007-01-01T23:59:59.000Z

31

Linear conductance through parallel coupled quantum dots  

Science Conference Proceedings (OSTI)

We study the electronic transport through two parallel coupled quantum dots (QDs), employing the X-boson treatment for the single impurity Anderson model. We compute the linear conductance (LC) and transmission coefficient for different regimes of the ... Keywords: 71.10.Ay, 71.27.+a, 73.21.La, 73.23.-b, Fano resonance, Kondo effect, Quantum dot, Transport, X-boson

R. Franco; J. Silva-Valencia; M. S. Figueira

2008-03-01T23:59:59.000Z

32

Light Touch: Controlling the Behavior of Quantum Dots  

Science Conference Proceedings (OSTI)

... dots, just as physicists have been doing with actual single atoms since the mid-1970s and, much more recently, with the artificial quantum dot ...

2011-05-02T23:59:59.000Z

33

Photoluminescence enhancement of quantum dots with photonic structures  

Science Conference Proceedings (OSTI)

Photoluminescence (PL) of CdSe/ZnS quantum dots (QDs) deposited on Si and photonic crystals with packed silica spheres, are investigated with the purpose of establishing enhancement of PL. Quantum dots with size ~2.4nm are introduced into the solution ... Keywords: CdSe quantum dots, Photonic band gap, Silica spheres, Surface quantum size effects

K. Liu; R. Tsu

2009-04-01T23:59:59.000Z

34

Quantum Teleportation in Quantum Dots System Hefeng Wang and Sabre Kais  

E-Print Network (OSTI)

Quantum Teleportation in Quantum Dots System Hefeng Wang and Sabre Kais Department of Chemistry of quantum teleportation protocol based on one-dimensional quantum dots system. Three quantum dots with three electrons are used to perform teleportation, the unknown qubit is encoded using one electron spin on quantum

Kais, Sabre

35

Quantum teleportation in one-dimensional quantum dots system Hefeng Wang, Sabre Kais *  

E-Print Network (OSTI)

Quantum teleportation in one-dimensional quantum dots system Hefeng Wang, Sabre Kais * Department of quantum teleportation protocol based on one-dimensional quantum dots system. Three quantum dots with three electrons are used to perform teleportation, the unknown qubit is encoded using one electron spin on quantum

Kais, Sabre

36

Nanostructured architectures for colloidal quantum dot solar cells  

E-Print Network (OSTI)

This thesis introduces a novel ordered bulk heterojunction architecture for colloidal quantum dot (QD) solar cells. Quantum dots are solution-processed nanocrystals whose tunable bandgap energies make them a promising ...

Jean, Joel, S.M. Massachusetts Institute of Technology

2013-01-01T23:59:59.000Z

37

Magnetic field switching in parallel quantum dots  

E-Print Network (OSTI)

We show that the Coulomb blockade in parallel dots pierced by magnetic flux $\\Phi$ completely blocks the resonant current for any value of $\\Phi$ except for integer multiples of the flux quantum $\\Phi_0$. This non-analytic (switching) dependence of the current on $\\Phi$ arises only when the dot states that carry the current are of the same energy. The time needed to reach the steady state, however, diverges when $\\Phi\\to n\\Phi_0$.

Feng Li; Xin-Qi Li; Wei-Min Zhang; S. A. Gurvitz

2008-03-11T23:59:59.000Z

38

Exciton binding energy in semiconductor quantum dots  

Science Conference Proceedings (OSTI)

In the adiabatic approximation in the context of the modified effective mass approach, in which the reduced exciton effective mass {mu} = {mu}(a) is a function of the radius a of the semiconductor quantum dot, an expression for the exciton binding energy E{sub ex}(a) in the quantum dot is derived. It is found that, in the CdSe and CdS quantum dots with the radii a comparable to the Bohr exciton radii a{sub ex}, the exciton binding energy E{sub ex}(a) is substantially (respectively, 7.4 and 4.5 times) higher than the exciton binding energy in the CdSe and CdS single crystals.

Pokutnii, S. I., E-mail: Pokutnyi_Sergey@inbox.ru [National Academy of Sciences of Ukraine, G.V. Kurdjumov Institute for Metal Physics (Ukraine)

2010-04-15T23:59:59.000Z

39

Infrared Quantum Dots** By Edward H. Sargent*  

E-Print Network (OSTI)

increasingly on mastery of the infrared spectral region. Fiber-optic communications systems rely on the low's progress in visible-light-emitting colloidal-quantum-dot synthesis, physical chemistry, and devices on applications and devices. The applications of interest surveyed include monolithic integration of fiber-optic

40

Magnetic field switching in parallel quantum dots  

E-Print Network (OSTI)

We show that the Coulomb blockade in parallel dots pierced by magnetic flux $\\Phi$ completely blocks the resonant current for any value of $\\Phi$ except for integer multiples of the flux quantum $\\Phi_0$. This non-analytic (switching) dependence of the current on $\\Phi$ arises only when the dot states that carry the current are of the same energy. The time needed to reach the steady state, however, diverges when $\\Phi\\to n\\Phi_0$. This current switch effect can find application in nano-circuit devices.

Li, Feng; Zhang, Wei-Min; Gurvitz, S A

2008-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "quantum dot tracers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

Hyper-parallel photonic quantum computation with coupled quantum dots  

E-Print Network (OSTI)

It is well known that a parallel quantum computer is more powerful than a classic computer. By far, there are some important works about the construction of universal quantum logic gates, key elements in quantum computation. However, all existing quantum gates are focused on operating on one degree of freedom (DOF) of quantum systems. Here, we investigate the possibility of achieving the scalable hyper-parallel quantum computation based on two DOFs of photon systems. We construct a deterministic hyper-controlled-not (hyper-CNOT) gate operating on both the spatial-mode and the polarization DOFs of a two-photon system simultaneously, by exploiting the giant optical circular birefringence induced by quantum-dot spins in double-sided optical microcavities as a result of cavity quantum electrodynamics. We analyze the experimental feasibility of this hyper-CNOT gate, concluding that it can be implemented with current technology.

Bao-Cang Ren; Fu-Guo Deng

2013-09-01T23:59:59.000Z

42

Mode Competition in Dual-Mode Quantum Dots Semiconductor Microlaser  

E-Print Network (OSTI)

This paper describes the modeling of quantum dots lasers with the aim of assessing the conditions for stable cw dual-mode operation when the mode separation lies in the THz range. Several possible models suited for InAs quantum dots in InP barriers are analytically evaluated, in particular quantum dots electrically coupled through a direct exchange of excitation by the wetting layer or quantum dots optically coupled through the homogeneous broadening of their optical gain. A stable dual-mode regime is shown possible in all cases when quantum dots are used as active layer whereas a gain medium of quantum well or bulk type inevitably leads to bistable behavior. The choice of a quantum dots gain medium perfectly matched the production of dual-mode lasers devoted to THz generation by photomixing.

Chusseau, Laurent; Viktorovitch, P; Letartre, Xavier

2013-01-01T23:59:59.000Z

43

Deposition of colloidal quantum dots by microcontact printing for LED display technology  

E-Print Network (OSTI)

This thesis demonstrates a new deposition method of colloidal quantum dots within a quantum dot organic light-emitting diode (QD-LED). A monolayer of quantum dots is microcontact printed as small as 20 ,Lm lines as well ...

Kim, LeeAnn

2006-01-01T23:59:59.000Z

44

Comment on "Analysis of quantum coherent semiconductor quantum dot p-i-n junction photovoltaic cells"  

E-Print Network (OSTI)

This is a comment on PRL paper by A.P. Kirk "Analysis of quantum coherent semiconductor quantum dot p-i-n junction photovoltaic cells"

Scully, Marlan O

2010-01-01T23:59:59.000Z

45

Quantum dots and radio-frequency electrometry in silicon.  

E-Print Network (OSTI)

??This thesis describes the development and demonstration of a new technique for the fabrication of well-defined quantum dots in a bulk silicon substrate, for potential… (more)

Angus, Susan J.

2008-01-01T23:59:59.000Z

46

Silicon-Germanium-Carbon Self Assembled Quantum Dot Growth ...  

Science Conference Proceedings (OSTI)

Feb 1, 2002 ... Silicon-Germanium-Carbon Self Assembled Quantum Dot Growth and Applications in Electronic Memory Devices by D.-W. Kim and S.

47

Session P: Quantum Effect Materials: InAs Dots - TMS  

Science Conference Proceedings (OSTI)

"Room Temperature Lasing From Excited Stated of InGaAs Quantum Dots:" RICHARD MIRIN, Arthur Gossard, John Bowers, ECE Department, MS100, ...

48

Stepwise Surface Assembly of Quantum Dot-Fullerene ...  

This stepwise surface assembly procedure results in high quality quantum dot-fullerene dimers with controllable linker length and a high yield of ...

49

Functionalized Quantum Dots for Molecular Profiling of Cancer ...  

Science Conference Proceedings (OSTI)

We report on different surface modification schemes and show how surface modification is key to producing stable suspensions of quantum dots in water.

50

Polarization Resolved Single Dot Spectroscopy of (211)B InAs Quantum Dots  

Science Conference Proceedings (OSTI)

We report on single dot spectroscopy of (211)B InAs quantum dots, grown by molecular beam epitaxy. The dots exhibit sharp emission lines, the origin of which has been identified. Polarization dependent microphotoluminescence spectra confirm fine structure splittings from 20{mu}eV down to the determination limit of our setup (10 {mu}eV).

Germanis, S.; Dialynas, G. E.; Deligeorgis, G.; Hatzopoulos, Z. [Physics Department, University of Crete, P.O. Box 2208, 71003 Heraklion, Crete (Greece); Savvidis, P. G.; Pelekanos, N. T. [Materials Science and Technology Department, University of Crete, P.O. Box 2208, 71003 Heraklion, Crete (Greece)

2011-12-23T23:59:59.000Z

51

Predicted Ultrafast Single Qubit Operations in Semiconductor Quantum Dots  

E-Print Network (OSTI)

Several recently proposed implementations of scalable quantum computation rely on the ability to manipulate the spin polarization of individual electrons in semiconductors. The most rapid single-spin-manipulation technique to date relies on the generation of an effective magnetic field via a spin-sensitive optical Stark effect. This approach has been used to split spin states in colloidal CdSe quantum dots and to manipulate ensembles of spins in ZnMnSe quantum wells with femtosecond optical pulses. Here we report that the process will produce a coherent rotation of spin in quantum dots containing a single electron. The calculated magnitude of the effective magnetic field depends on the dot bandgap and the strain. We predict that in InAs/InP dots, for reasonable experimental parameters, the magnitude of the rotation is sufficient and the intrinsic error is low enough for them to serve as elements of a quantum dot based quantum computer.

C. E. Pryor; M. E. Flatté

2002-11-25T23:59:59.000Z

52

NREL: News - NREL and Partners Demonstrate Quantum Dots that Assemble  

NLE Websites -- All DOE Office Websites (Extended Search)

113 113 NREL and Partners Demonstrate Quantum Dots that Assemble Themselves Surprising breakthrough could bolster quantum photonics, solar cell efficiency February 8, 2013 Scientists from the U.S. Department of Energy's National Renewable Energy Laboratory and other labs have demonstrated a process whereby quantum dots can self-assemble at optimal locations in nanowires, a breakthrough that could improve solar cells, quantum computing, and lighting devices. A paper on the new technology, "Self-assembled Quantum Dots in a Nanowire System for Quantum Photonics," appears in the current issue of the scientific journal Nature Materials. Quantum dots are tiny crystals of semiconductor a few billionths of a meter in diameter. At that size they exhibit beneficial behaviors of quantum

53

Holonomic quantum computation with electron spins in quantum dots  

Science Conference Proceedings (OSTI)

With the help of the spin-orbit interaction, we propose a scheme to perform holonomic single-qubit gates on the electron spin confined to a quantum dot. The manipulation is done in the absence (or presence) of an applied magnetic field. By adiabatic changing the position of the confinement potential, one can rotate the spin state of the electron around the Bloch sphere in semiconductor heterostructures. The dynamics of the system is equivalent to employing an effective non-Abelian gauge potential whose structure depends on the type of the spin-orbit interaction. As an example, we find an analytic expression for the electron spin dynamics when the dot is moved around a circular path (with radius R) on the two dimensional electron gas (2DEG) and show that all single-qubit gates can be realized by tuning the radius and orientation of the circular paths. Moreover, using the Heisenberg exchange interaction, we demonstrate how one can generate two-qubit gates by bringing two quantum dots near each other, yielding a scalable scheme to perform quantum computing on arbitrary N qubits. This proposal shows a way of realizing holonomic quantum computers in solid-state systems.

Golovach, Vitaly N. [Arnold Sommerfeld Center for Theoretical Physics and Center for Nanoscience Department of Physics, Ludwig-Maximilians-Universitaet, Theresienstrasse 37, D-80333 Munich (Germany); Borhani, Massoud [Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel (Switzerland); Department of Physics, University at Buffalo, SUNY, Buffalo, New York 14260-1500 (United States); Loss, Daniel [Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel (Switzerland)

2010-02-15T23:59:59.000Z

54

QUANTUM DOT MULTI-SECTION LIGHT EMITTERS YONGCHUN XIN  

E-Print Network (OSTI)

such as lasers, super-luminescent light emitting diodes, detectors, amplifiers, and solar cells [19, 20]. 1QUANTUM DOT MULTI-SECTION LIGHT EMITTERS BY YONGCHUN XIN B.S., Physics, Peking University, 1996 M. To my son, Alex, you are the greatest gift I have. #12;QUANTUM DOT MULTI-SECTION LIGHT EMITTERS

New Mexico, University of

55

Improving Intrinsic Decoherence in Multi-Quantum-Dot Charge Qubits  

E-Print Network (OSTI)

We discuss decoherence in charge qubits formed by multiple lateral quantum dots in the framework of the spin-boson model and the Born-Markov approximation. We consider the intrinsic decoherence caused by the coupling to bulk phonon modes. Two distinct quantum dot configurations are studied: (i) Three quantum dots in a ring geometry with one excess electron in total and (ii) arrays of quantum dots where the computational basis states form multipole charge configurations. For the three-dot qubit, we demonstrate the possibility of performing one- and two-qubit operations by solely tuning gate voltages. Compared to the proposal by DiVincenzo {\\it et al.} involving a linear three-dot spin qubit, the three-dot charge qubit allows for less overhead on two-qubit operations. For small interdot tunnel amplitudes, the three-dot qubits have $Q$ factors much higher than those obtained for double dot systems. The high-multipole dot configurations also show a substantial decrease in decoherence at low operation frequencies when compared to the double-dot qubit.

Martina Hentschel; Diego C. B. Valente; Eduardo R. Mucciolo; Harold U. Baranger

2007-05-28T23:59:59.000Z

56

Numerical simulation of optical feedback on a quantum dot lasers  

Science Conference Proceedings (OSTI)

We use multi-population rate equations model to study feedback oscillations in the quantum dot laser. This model takes into account all peculiar characteristics in the quantum dots such as inhomogeneous broadening of the gain spectrum, the presence of the excited states on the quantum dot and the non-confined states due to the presence of wetting layer and the barrier. The contribution of quantum dot groups, which cannot follow by other models, is simulated. The results obtained from this model show the feedback oscillations, the periodic oscillations which evolves to chaos at higher injection current of higher feedback levels. The frequency fluctuation is attributed mainly to wetting layer with a considerable contribution from excited states. The simulation shows that is must be not using simple rate equation models to express quantum dots working at excited state transition.

Al-Khursan, Amin H., E-mail: ameen_2all@yahoo.com [Thi-Qar University, Nassiriya Nanotechnology Research Laboratory (NNRL), Science College (Iraq); Ghalib, Basim Abdullattif [Babylon University, Laser Physics Department, Science College for Women (Iraq); Al-Obaidi, Sabri J. [Al-Mustansiriyah University, Physics Department, Science College (Iraq)

2012-02-15T23:59:59.000Z

57

Entanglement distribution for a practical quantum-dot-based quantum processor architecture  

E-Print Network (OSTI)

We propose a quantum dot architecture for enabling universal quantum information processing. Quantum registers, consisting of arrays of vertically stacked self-assembled semiconductor quantum dots, are connected by chains of in-plane self-assembled dots. We propose an entanglement distributor, a device for producing and distributing maximally entangled qubits on demand, communicated through in-plane dot chains. This enables the transmission of entanglement to spatially separated register stacks, providing a resource for the realisation of a sizeable quantum processor built from coupled register stacks of practical size. Our entanglement distributor could be integrated into many of the present proposals for self-assembled quantum dot-based quantum computation. Our device exploits the properties of simple, relatively short, spin-chains and does not require microcavities. Utilizing the properties of self-assembled quantum dots, after distribution the entanglement can be mapped into relatively long lived spin qubits and purified, providing a flexible, distributed, off-line resource.

Timothy P. Spiller; Irene D'Amico; Brendon W. Lovett

2006-01-19T23:59:59.000Z

58

Symmetric quantum dots as efficient sources of highly entangled photons  

E-Print Network (OSTI)

An ideal source of entangled photon pairs combines the perfect symmetry of an atom with the convenient electrical trigger of light sources based on semiconductor quantum dots. We create a naturally symmetric quantum dot cascade that emits highly entangled photon pairs on demand. Our source consists of strain-free GaAs dots self-assembled on a triangular symmetric (111)A surface. The emitted photons strongly violate Bell's inequality and reveal a fidelity to the Bell state as high as 86 (+-2) % without postselection. This result is an important step towards scalable quantum-communication applications with efficient sources.

T. Kuroda; T. Mano; N. Ha; H. Nakajima; H. Kumano; B. Urbaszek; M. Jo; M. Abbarachi; Y. Sakuma; K. Sakoda; I. Suemune; X. Marie; T. Amand

2013-02-26T23:59:59.000Z

59

Etched quantum dots for all-optical and electro-optical switches  

Science Conference Proceedings (OSTI)

We present progress to date in the production of quantum dots etched from multiple quantum well structures for use in all-optical and electro-optical switches. Details of fabrication and comparisons to self-assembled quantum dot materials are described, ... Keywords: All-optical, Deep etching, Nanofabrication, Quantum boxes, Quantum dots

Nathan Bickel; Patrick LiKamWa

2008-03-01T23:59:59.000Z

60

Effective cavity pumping from weakly coupled quantum dots  

E-Print Network (OSTI)

We derive the effective cavity pumping and decay rates for the master equation of a quantum dot-microcavity system in presence of $N$ weakly coupled dots. We show that the in-flow of photons is not linked to the out-flow by thermal equilibrium relationships.

del Valle, E

2010-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "quantum dot tracers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

Arithmetic Design on Quantum-Dot Cellular Automata Nanotechnology  

Science Conference Proceedings (OSTI)

Quantum-dot cellular automata nanotechnology promises molecular digital circuits with ultra-high clock frequencies, to replace the traditional approaches reaching their physical limits. Although large scale utilization requires still several breakthroughs, ... Keywords: Nanotechnology, arithmetic, digital design

Ismo Hänninen; Jarmo Takala

2008-07-01T23:59:59.000Z

62

ZnO-graphene Hybrid Quantum Dots Light Emitting Diode  

Science Conference Proceedings (OSTI)

Presentation Title, ZnO-graphene Hybrid Quantum Dots Light Emitting Diode. Author(s), Won Kook Choi, Dong-Ick Son, Soon-Nam Kwon. On-Site Speaker ...

63

Growth of cubic GaN quantum dots  

SciTech Connect

Zinc-blende GaN quantum dots were grown on 3C-AlN(001) by two different methods in a molecular beam epitaxy system. The quantum dots in method A were fabricated by the Stranski-Krastanov growth process. The quantum dots in method B were fabricated by droplet epitaxy, a vapor-liquid-solid process. The density of the quantum dots was controllable in a range of 10{sup 8} cm{sup -2} to 10{sup 12} cm{sup -2}. Reflection high energy electron diffraction analysis confirmed the zinc-blende crystal structure of the QDs. Photoluminescence spectroscopy revealed the optical activity of the QDs, the emission energy was in agreement with the exciton ground state transition energy of theoretical calculations.

Schupp, T.; Lischka, K.; As, D. J. [Universitaet Paderborn, Department Physik, Warburger Str.100, 33095 Paderborn (Germany); Meisch, T.; Neuschl, B.; Feneberg, M.; Thonke, K. [Institut fuer Quantenmaterie, Universitaet Ulm, 89069 Ulm (Germany)

2010-11-01T23:59:59.000Z

64

Hybrid organic/quantum dot thin film structures and devices  

E-Print Network (OSTI)

Organic light emitting diodes have undergone rapid advancement over the course of the past decade. Similarly, quantum dot synthesis has progressed to the point that room temperature highly efficient photoluminescence can ...

Coe-Sullivan, Seth (Seth Alexander)

2005-01-01T23:59:59.000Z

65

Argonne CNM News: Enhanced Light-Harvesting in Quantum Dot -...  

NLE Websites -- All DOE Office Websites (Extended Search)

Enhanced Light-Harvesting in Quantum Dot-Metal Organic Frameworks A schematic of directional energy (exciton) migration in the MOF, along with the porphyrin building-blocks of the...

66

Quantum dot conjugates in a sub-micrometer fluidic channel  

DOE Patents (OSTI)

A nanofluidic channel fabricated in fused silica with an approximately 500 nm square cross section was used to isolate, detect and identify individual quantum dot conjugates. The channel enables the rapid detection of every fluorescent entity in solution. A laser of selected wavelength was used to excite multiple species of quantum dots and organic molecules, and the emission spectra were resolved without significant signal rejection. Quantum dots were then conjugated with organic molecules and detected to demonstrate efficient multicolor detection. PCH was used to analyze coincident detection and to characterize the degree of binding. The use of a small fluidic channel to detect quantum dots as fluorescent labels was shown to be an efficient technique for multiplexed single molecule studies. Detection of single molecule binding events has a variety of applications including high throughput immunoassays.

Stavis, Samuel M. (Ithaca, NY); Edel, Joshua B. (Brookline, MA); Samiee, Kevan T. (Ithaca, NY); Craighead, Harold G. (Ithaca, NY)

2008-07-29T23:59:59.000Z

67

Binding energy calculation of excitonic trions in spherical quantum dots with the quantum adiabatic theorem  

Science Conference Proceedings (OSTI)

The stability of the charged excitons X+ and X- as a function of the spherical quantum dot radius R and also as a function of the effective mass ratio ? is studied with a formulation of the Hartree Fock approximation ... Keywords: bound excitons, excitons, quantum dots

S. Baskoutas; A. F. Terzis

2005-08-01T23:59:59.000Z

68

Surface Induced Magnetism in Quantum Dots  

SciTech Connect

The study of nanometer sized semiconductor crystallites, also known as quantum dots (QDs), has seen rapid advancements in recent years in scientific disciplines ranging from chemistry, physics, biology, materials science, and engineering. QD materials of CdSe, ZnSe, InP, as well as many others, can be prepared in the size range of 1-10 nm producing uniform, nearly monodisperse materials that are typically coated with organic molecules [1-3]. The strength of charge carrier confinement, which dictates the size-dependent properties, in these QDs depends on the nature of the material and can be correlated to the Bohr radius for the system of interest. For instance, the Bohr radius for CdSe is {approx} 5 nm, while in the more covalent structure of InP, the Bohr radius approaches {approx} 10 nm. The study of CdSe QDs has been particularly extensive during the last decade because they exhibit unique and tunable optical properties and are readily synthesized with high-crystallinity and narrow size dispersions. Although the core electronic properties of CdSe are explained in terms of the quantum confinement model, experimental efforts to elucidate the surface structure of these materials have been limited. Typically, colloidal CdSe QDs are coated with an organic surfactant, which typically consists of an organo-phosphine, -thiol, or -amine, that has the function of energetically relaxing defect states via coordination to partially coordinated surface atoms. The organic surfactant also acts to enhance carrier confinement and prevent agglomeration of the particles. Chemically, it has been shown that the bonding of the surfactant to the CdSe QD occurs through Cd atoms resulting cleavage of the Se atoms and formation of a Cd-rich (i.e. non-stoichiometric) particle [5].

Meulenberg, R W; Lee, J I

2009-08-20T23:59:59.000Z

69

THE FABRICATION AND ANALYSIS OF QUANTUM-DOT THIN FILM LIGHT EMITTING DIODES FOR USE IN DISPLAYS TECHNOLOGIES.  

E-Print Network (OSTI)

??The quantum dot has many applications, one of which is the light emitting diode. Quantum dot light emitting diodes were fabricated for their use in… (more)

Pickering, Shawn

2011-01-01T23:59:59.000Z

70

Intermediate-band photosensitive device with quantum dots having tunneling barrier embedded in organic matrix  

DOE Patents (OSTI)

A plurality of quantum dots each have a shell. The quantum dots are embedded in an organic matrix. At least the quantum dots and the organic matrix are photoconductive semiconductors. The shell of each quantum dot is arranged as a tunneling barrier to require a charge carrier (an electron or a hole) at a base of the tunneling barrier in the organic matrix to perform quantum mechanical tunneling to reach the respective quantum dot. A first quantum state in each quantum dot is between a lowest unoccupied molecular orbital (LUMO) and a highest occupied molecular orbital (HOMO) of the organic matrix. Wave functions of the first quantum state of the plurality of quantum dots may overlap to form an intermediate band.

Forrest, Stephen R. (Ann Arbor, MI)

2008-08-19T23:59:59.000Z

71

High Operating Temperature Quantum-Dot Infrared Photodetector Using Advanced Capping Techniques  

Science Conference Proceedings (OSTI)

We demonstrate an improvement in the operating temperature of a quantum dot-in-a-well (DWELL)-based infrared photodetector with spectral response observable till 250 K. This improvement was achieved through engineering the dot geometry and the quantum ...

Jiayi Shao; Thomas E. Vandervelde; Woo-Yong Jang; Andreas Stintz; Sanjay Krishna

2011-09-01T23:59:59.000Z

72

Improving PbS Quantum Dot Solar Cell Power Conversion Efficiency...  

NLE Websites -- All DOE Office Websites (Extended Search)

research team developed a new process that improves the efficiency of PbS quantum dot solar power conversion. Key Result By using a transition metal oxide in the quantum dot...

73

Novel type-II nanocrystal quantum dots and versatile oligomeric phosphine ligands  

E-Print Network (OSTI)

This thesis describes the syntheses, characterizations, and applications of novel type-II quantum dots and versatile oligomeric phosphine ligands. Type-II band engineered quantum dots (CdTe/CdSe(core/shell) and ...

Kim, Sungjee, 1972-

2003-01-01T23:59:59.000Z

74

Fabrication and optimization of light emitting devices with core-shell quantum dots  

E-Print Network (OSTI)

Quantum dot light emitting devices (QD-LEDs) are promising options for the next generation of solid state lighting, color displays, and other optoelectronic applications. Overcoating quantum dots (QDs) -- semiconducting ...

Song, Katherine Wei

2013-01-01T23:59:59.000Z

75

Quantum Dots, Carbon Dots and other Luminescent Nanostructures  

Science Conference Proceedings (OSTI)

Oct 28, 2013 ... The latest development in interfacial electronic structure and quantum confinement effects of visible light-active all-oxide heteronanostructures ...

76

Simultaneous Spin-Charge Relaxation in Double Quantum Dots  

E-Print Network (OSTI)

We investigate phonon-induced spin and charge relaxation mediated by spin-orbit and hyperfine interactions for a single electron confined within a double quantum dot. A simple toy model incorporating both direct decay to the ground state of the double dot and indirect decay via an intermediate excited state yields an electron spin relaxation rate that varies non-monotonically with the detuning between the dots. We confirm this model with experiments performed on a GaAs double dot, demonstrating that the relaxation rate exhibits the expected detuning dependence and can be electrically tuned over several orders of magnitude. Our analysis suggests that spin-orbit mediated relaxation via phonons serves as the dominant mechanism through which the double-dot electron spin-flip rate varies with detuning.

V. Srinivasa; K. C. Nowack; M. Shafiei; L. M. K. Vandersypen; J. M. Taylor

2013-03-07T23:59:59.000Z

77

Generation of even harmonics in coupled quantum dots  

Science Conference Proceedings (OSTI)

Using the spatial-temporal symmetry principle we developed recently, we propose an effective scheme for even-harmonics generation in coupled quantum dots. The relative intensity of odd and even harmonic components in the emission spectrum can be controlled by tuning the dipole couplings among the dots, which can be realized in experiments by careful design of the nanostructures. In particular, pure 2nth harmonics and (2n+1)th harmonics (where n is an integer) can be generated simultaneously with polarizations in two mutual perpendicular directions in our systems. An experimental design of the coupled dots system is presented.

Guo Shifang; Duan Suqing; Yang Ning; Chu Weidong; Zhang Wei [Institute of Applied Physics and Computational Mathematics, P.O. Box 8009, Beijing 100088 (China)

2011-07-15T23:59:59.000Z

78

Los Alamos researchers unravel the mystery of quantum dot blinking  

NLE Websites -- All DOE Office Websites (Extended Search)

Researchers unravel the mystery of quantum dot blinking Researchers unravel the mystery of quantum dot blinking Los Alamos researchers unravel the mystery of quantum dot blinking Most exciting is that the Los Alamos researchers have shown that blinking can be controlled and even completely suppressed electrochemically. November 9, 2011 Los Alamos National Laboratory sits on top of a once-remote mesa in northern New Mexico with the Jemez mountains as a backdrop to research and innovation covering multi-disciplines from bioscience, sustainable energy sources, to plasma physics and new materials. Los Alamos National Laboratory sits on top of a once-remote mesa in northern New Mexico with the Jemez mountains as a backdrop to research and innovation covering multi-disciplines from bioscience, sustainable energy

79

Self-organized formation of quantum dots of a material on a substrate  

DOE Patents (OSTI)

Systems and methods are described for fabricating arrays of quantum dots. A method for making a quantum dot device, includes: forming clusters of atoms on a substrate; and charging the clusters of atoms such that the clusters of atoms repel one another. The systems and methods provide advantages because the quantum dots can be ordered with regard to spacing and/or size.

Zhang, Zhenyu (232 Long Bow Rd., Knoxville, TN 37922); Wendelken, John F. (925 Suwanee Rd., Knoxville, TN 37923); Chang, Ming-Che (F4-2, No. 178 Sec 5 Minsheng East Rd., Taipei, TW); Pai, Woei Wu (1F, No. 17, Alley 11, Lane 202, Ming Chyuan Rd., Pan Chou City, Taipei County, TW)

2001-01-01T23:59:59.000Z

80

Anti-correlation for Conductance Fluctuations in Chaotic Quantum Dots  

E-Print Network (OSTI)

We investigate the correlation functions of mesoscopic electronic transport in open chaotic quantum dots with finite tunnel barriers in the crossover between Wigner-Dyson ensembles. Using an analytical stub formalism, we show the emergence of a depletion/amplification of conductance fluctuations as a function of tunnel barriers, for both parametric variations of electron energy or magnetoconductance fields. Furthermore, even for pure Dyson ensembles, correlation functions of conductance fluctuations in chaotic quantum dots can exhibit anti-correlation. Experimental support to our findings is pointed out.

A. L. R. Barbosa; M. S. Hussein; J. G. G. S. Ramos

2013-06-21T23:59:59.000Z

Note: This page contains sample records for the topic "quantum dot tracers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

Entanglement dynamics of photon pairs emitted from quantum dots  

Science Conference Proceedings (OSTI)

We present a model that describes states of photon pairs, which have been generated by biexciton cascade decays of self-assembled quantum dots, the use of which yields a finding that agrees well with the experimental result. Furthermore, we calculate the concurrence and determine the temperature behavior associated with the so-called entanglement sudden death that prevents quantum dots emitting entangled photon pairs at raised temperatures. The relationship between the fine-structure splitting and the sudden death temperature is also provided.

Zou, Yang; Gong, Ming; Li, Chuan-Feng; Chen, Geng; Tang, Jian-Shun; Guo, Guang-Can [Key Laboratory of Quantum Information, University of Science and Technology of China, CAS, Hefei 230026 (China)

2010-06-15T23:59:59.000Z

82

Nonclassical correlation of cascaded photon pairs emitted from quantum dots  

SciTech Connect

We studied the quantum correlation of the photon pairs generated by biexciton cascade decays of self-assembled quantum dots, and determined the correlation sudden-change temperature, which is shown to be independent of the background noise, far lower than the entanglement sudden-death temperature, and therefore, easier to be observed in experiments. The relationship between the fine-structure splitting and the sudden-change temperature is also provided.

Li, Chuan-Feng; Zou, Yang; Xu, Jin-Shi; Ge, Rong-Chun; Guo, Guang-Can [Key Laboratory of Quantum Information, University of Science and Technology of China, CAS, Hefei 230026 (China)

2011-11-15T23:59:59.000Z

83

Deformation potentials of CdSe quantum dots  

E-Print Network (OSTI)

a v (in eV) of zinc-blende CdSe. SEPM PW PW+d a a LAPW Expt>4: The size dependence of — a of C B M state of CdSe QDs. vDeformation potentials of CdSe quantum dots Jingbo L i and L

Li, Jingbo; Wang, Lin-Wang

2004-01-01T23:59:59.000Z

84

Quantum dot-based nanomaterials for biological imaging  

E-Print Network (OSTI)

Quantum dot-based fluorescent probes were synthesized and applied to biological imaging in two distinct size regimes: (1) 100-1000 nm and (2) < 10 nm in diameter. The larger diameter range was accessed by doping CdSe/ZnS ...

Zimmer, John P. (John Philip)

2006-01-01T23:59:59.000Z

85

Eigenstate selection in open quantum dot systems: using the Landauer formalism as a spectroscopic probe  

Science Conference Proceedings (OSTI)

We show that transport in open quantum dots can be mediated by single eigenstates, even when the leads allow several propagating modes. The broadening of these states can be virtually independent of lead width. While sets of completely broadened states ... Keywords: device modeling, quantum chaos, quantum dots, quantum transport

R. Akis; J. P. Bird; D. K. Ferry

2002-08-01T23:59:59.000Z

86

Quantum Dot Light-emitting Diodes  

Science Conference Proceedings (OSTI)

About this Abstract. Meeting, Materials Science & Technology 2013. Symposium, Optical Nanomaterials for Photonics/Biophotonics. Presentation Title, Quantum ...

87

Comparison of quantum confinement effects between quantum wires and dots  

E-Print Network (OSTI)

? wire . Si GaAs InAs InP CdSe CdS CdTe ? dot ? dot ? wire ?systems like InP and CdSe. Here, we like to address thesematerials: Si, InP, InAs, GaAs, CdSe, CdS, and CdTe. Unlike

Li, Jingbo; Wang, Lin-Wang

2004-01-01T23:59:59.000Z

88

NREL Certifies First All-Quantum-Dot Photovoltaic Cell; Demonstrates Stability, Performance (Fact Sheet)  

SciTech Connect

Researchers at the National Renewable Energy Laboratory (NREL) have certified the first all-quantum-dot photovoltaic cell, which was based on lead sulfide and demonstrated reasonable quantum dot solar cell performance for an initial efficiency measurement along with good stability. The certified open-circuit voltage of the quantum dot cell is greater than that possible from bulk lead sulfide because of quantum confinement.

Not Available

2011-02-01T23:59:59.000Z

89

Surface acoustic wave controlled carrier injection into self-assembled quantum dots and quantum posts  

E-Print Network (OSTI)

We report on recent progress in the acousto-electrical control of self-assembled quantum dot and quantum post using radio frequency surface acoustic waves (SAWs). We show that the occupancy state of these optically active nanostructures can be controlled via the SAW-induced dissociation of photogenerated excitons and the resulting sequential bipolar carrier injection which strongly favors the formation of neutral excitons for quantum posts in contrast to conventional quantum dots. We demonstrate high fidelity preparation of the neutral biexciton which makes this approach suitable for deterministic entangled photon pair generation. The SAW driven acoustic charge conveyance is found to be highly efficient within the wide quantum well surrounding the quantum posts. Finally we present the direct observation of acoustically triggered carrier injection into remotely positioned, individual quantum posts which is required for a low-jitter SAW-triggered single photon source.

Hubert J. Krenner; Stefan Völk; Florian J. R. Schülein; Florian Knall; Achim Wixforth; Dirk Reuter; Andreas D. Wieck; Hyochul Kim; Tuan A. Truong; Pierre M. Petroff

2011-10-20T23:59:59.000Z

90

Light Dynamics in a Quantum Dot  

Science Conference Proceedings (OSTI)

Single Photon from a Quantum Emitter? It's a Matter of Timing . . . ... They also created a model to explain the physics of the phenomenon. ...

2013-04-08T23:59:59.000Z

91

Approaches to Future Generation Photovoltaics and Solar Fuels: Quantum Dots, Arrays, and Quantum Dot Solar Cells  

Science Conference Proceedings (OSTI)

One potential, long-term approach to more efficient and lower cost future generation solar cells for solar electricity and solar fuels is to utilize the unique properties of quantum dots (QDs) to control the relaxation pathways of excited states to enhance multiple exciton generation (MEG). We have studied MEG in close-packed PbSe QD arrays where the QDs are electronically coupled in the films and thus exhibit good transport while still maintaining quantization and MEG. We have developed simple, all-inorganic solution-processable QD solar cells that produce large short-circuit photocurrents and power conversion efficiencies above 5% via nanocrystalline p-n junctions. These solar cells show QYs for photocurrent that exceed 100% in the photon energy regions where MEG is possible; the photocurrent MEG QYs as a function of photon energy match those determined via time-resolved spectroscopy Recent analyses of the major effect of MEG combined with solar concentration on the conversion efficiency of solar cells will also be discussed.

Semonin, O.; Luther, J.; Beard, M.; Johnson, J.; Gao, J.; Nozik, A.

2012-01-01T23:59:59.000Z

92

The effects of quantum dot coverage in InAs/(In)GaAs nanostructures for long wavelength emission  

Science Conference Proceedings (OSTI)

We present a study on the effects of quantum dot coverage on the properties of InAs dots embedded in GaAs and in metamorphic In0.15Ga0.85As confining layers grown by molecular beam epitaxy on GaAs substrates. We show that redshifted ... Keywords: Long wavelength emission, Molecular beam epitaxy, Quantum dot ripening, Quantum dots

G. Trevisi; L. Seravalli; P. Frigeri; M. Prezioso; J. C. Rimada; E. Gombia; R. Mosca; L. Nasi; C. Bocchi; S. Franchi

2009-03-01T23:59:59.000Z

93

Spectrum of electron-hole states of the Si/Ge structure with Ge quantum dots  

Science Conference Proceedings (OSTI)

The lateral photoconductivity spectra of Si/Ge multilayer structures with Ge quantum dots of various sizes are investigated. We observed optical transition lines between the hole levels of quantum dots and electronic states of Si. This enabled us to construct a detailed energy level diagram of the electron-hole spectrum of the Si/Ge structures. It is shown that the hole levels of Ge quantum dots are successfully described by the 'quantum box' model using the actual sizes of Ge islands. It I found that the position of the longwavelength photosensitivity boundary of Si/Ge structures with Ge quantum dots can be controlled by changing the growth parameters.

Talochkin, A. B., E-mail: tal@thermo.isp.nsc.ru; Chistokhin, I. B., E-mail: igor@thermo.isp.nsc.ru [Russian Academy of Sciences, Institute of Semiconductor Physics, Siberian Branch (Russian Federation)

2011-09-15T23:59:59.000Z

94

Photoconductivity of Si/Ge multilayer structures with Ge quantum dots pseudomorphic to the Si matrix  

SciTech Connect

Longitudinal photoconductivity spectra of Si/Ge multilayer structures with Ge quantum dots grown pseudomorphically to the Si matrix are studied. Lines of optical transitions between hole levels of quantum dots and Si electronic states are observed. This allowed us to construct a detailed energy-level diagram of electron-hole levels of the structure. It is shown that hole levels of pseudomorphic Ge quantum dots are well described by the simplest 'quantum box' model using actual sizes of Ge islands. The possibility of controlling the position of the long-wavelength photosensitivity edge by varying the growth parameters of Si/Ge structures with Ge quantum dots is determined.

Talochkin, A. B., E-mail: tal@thermo.isp.nsc.ru; Chistokhin, I. B. [Russian Academy of Sciences, Rzhanov Institute of Semiconductor Physics, Siberian Branch (Russian Federation)

2011-07-15T23:59:59.000Z

95

Angular momentum transfer between a circularly polarized photon and an electron spin in double quantum dots  

SciTech Connect

We propose an experimental scheme of photon-spin quantum interface using a semiconductor double quantum dot. A polarized electron spin is excited by a circularly polarized photon. We detect the spin state applying Pauli spin blockade which is often employed to detect orientation of a single electron spin in double quantum dots.

Asayama, T. [Department of Applied Physics and QPEC, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo (Japan); Solid State Memories Development Dept, Sony Corporation, Atsugi, Kanagawa (Japan); Fujita, T.; Kiyama, H.; Oiwa, A. [Department of Applied Physics and QPEC, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo (Japan); Tarucha, S. [Department of Applied Physics and QPEC, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo (Japan); Institute for Nano Quantum Electronics, University of Tokyo, 4-6-1, Komaba, Meguro-ku, Tokyo (Japan)

2011-12-23T23:59:59.000Z

96

Entanglement in GaAs and CdSe quantum dots: Exact calculations and DFT approximations  

Science Conference Proceedings (OSTI)

We consider two electrons confined in spherical GaAs and CdSe quantum dots and calculate their ground-state spatial entanglement exactly within a parabolic confinement model. We propose a perturbative scheme to approximate the above entanglement within ... Keywords: Density-functional theory, Entanglement, Quantum dots, Quantum information, Semiconductors

J. P. Coe; A. Sudbery; I. D'Amico

2009-03-01T23:59:59.000Z

97

All-Optical Measurement Based QIP in Quantum Dots  

E-Print Network (OSTI)

Parity measurements on qubits can generate the entanglement resource necessary for scalable quantum computation. Here we describe a method for fast optical parity measurements on electron spin qubits within coupled quantum dots. The measurement scheme, which can be realised with existing technology, consists of the optical excitation of excitonic states followed by monitored relaxation. Conditional on the observation of a photon, the system is projected into the odd/even parity subspaces. Our model incorporates all the primary sources of error, including detector inefficiency, effects of spatial separation and non-resonance of the dots, and also unwanted excitations. Through an analytical treatment we establish that the scheme is robust to such effects. Two applications are presented: a realisation of a CNOT gate, and a technique for growing large scale graph states.

Avinash Kolli; Brendon W. Lovett; Simon C. Benjamin; Thomas M. Stace

2006-07-04T23:59:59.000Z

98

All-Optical Measurement Based QIP in Quantum Dots  

E-Print Network (OSTI)

Parity measurements on qubits can generate the entanglement resource necessary for scalable quantum computation. Here we describe a method for fast optical parity measurements on electron spin qubits within coupled quantum dots. The measurement scheme, which can be realised with existing technology, consists of the optical excitation of excitonic states followed by monitored relaxation. Conditional on the observation of a photon, the system is projected into the odd/even parity subspaces. Our model incorporates all the primary sources of error, including detector inefficiency, effects of spatial separation and non-resonance of the dots, and also unwanted excitations. Through an analytical treatment we establish that the scheme is robust to such effects. Two applications are presented: a realisation of a CNOT gate, and a technique for growing large scale graph states.

Kolli, A; Lovett, B W; Stace, T M; Benjamin, Simon C.; Kolli, Avinash; Lovett, Brendon W.; Stace, Tom M.

2006-01-01T23:59:59.000Z

99

High fidelity gates in quantum dot spin qubits  

E-Print Network (OSTI)

Several logical qubits and quantum gates have been proposed for semiconductor quantum dots controlled by voltages applied to top gates. Differences between the schemes can make it difficult to compare them meaningfully. Here we develop a theoretical framework to evaluate disparate qubit-gating schemes on an equal footing. We apply the procedure to two types of double-dot qubits: the singlet-triplet (ST) and the semiconducting quantum dot hybrid qubit. We investigate three quantum gates that flip the qubit state: a DC pulsed gate, an AC gate based on logical qubit resonance (LQR), and a gate-like process known as stimulated Raman adiabatic passage (STIRAP). These gates are all mediated by an exchange interaction that depends on a small number of experimental control parameters, including the interdot tunnel coupling $g$ and the detuning $\\epsilon$, which sets the energy difference between the dots. Our procedure has two steps. First, we optimize the gate fidelity ($f$) for fixed $g$ as a function of the other control parameters; this yields an $f^\\text{opt}(g)$ that is universal for different types of gates. Next, we identify physical constraints on the control parameters; this yields an upper bound $f^\\text{max}$ that is specific to the qubit-gate combination. We show that similar gate fidelities ($\\sim 99.5$%) should be attainable for ST qubits in isotopically purified Si, and for hybrid qubits in natural Si. Considerably lower fidelities are obtained for GaAs devices, due to the fluctuating magnetic fields $\\Delta B$ produced by nuclear spins.

Teck Seng Koh; S. N. Coppersmith; Mark Friesen

2013-07-31T23:59:59.000Z

100

Efficient multi-exciton emission from quantum dots.  

Science Conference Proceedings (OSTI)

The fundamental spontaneous emission rate an emitter can be modified by its photonic environment. By enhancing the spontaneous emission rate, there is a possibility of extracting multi-exciton energies through radiative decay. In this report, we explore using high Q and small volume cavities to enhance the spontaneous emission rate. We observed greater than 50 folds enhancement in the spontaneous emission from photonic crystal waveguide or microcavity using close-packed monolayer of PbS quantum dot emitters.

Luk, Ting Shan

2010-09-01T23:59:59.000Z

Note: This page contains sample records for the topic "quantum dot tracers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

An iterative method for single and vertically stacked semiconductor quantum dots simulation  

Science Conference Proceedings (OSTI)

We present in this paper a computational effective nonlinear iterative method for calculating the electron energy spectra in single and vertically stacked InAs/GaAs semiconductor quantum dots. The physical model problem is formulated with the effective ... Keywords: Coupling effect, Electronic structure, Energy spectra, Modelling and simulation, Multishift QR method, Nonlinear eigenvalue problem, Semiconductor nanostructure, Single quantum dot, Vertically stacked quantum dot, Wave function

Yiming Li

2005-10-01T23:59:59.000Z

102

Features of the electronic spectrum in a type-I core - shell quantum dot  

Science Conference Proceedings (OSTI)

The model is proposed, which allows one to solve the problem of finding the energy spectrum and the wave function of an electron in a type-I core - shell quantum dot. It is shown that the size of the core and shell can serve as control parameters for the optimisation of the energy structure of the quantum dot in order to obtain the real structures with desired electrophysical and optical properties. (quantum dots)

Igoshina, S E; Karmanov, A A [Penza State University, Penza (Russian Federation)

2013-01-31T23:59:59.000Z

103

Quantum Dots Promise to Significantly Boost Photovoltaic Efficiencies; The Spectrum of Clean Energy Innovation (Fact Sheet)  

SciTech Connect

Fact sheet describing NREL's discovery that quantum dots--semiconductor nanocrystals--can dramatically increase the efficiency of converting sunlight to electricity.

Not Available

2010-06-01T23:59:59.000Z

104

Quantum Dots Promise to Significantly Boost Photovoltaic Efficiencies; The Spectrum of Clean Energy Innovation (Fact Sheet)  

SciTech Connect

Fact sheet describing NREL's discovery that quantum dots--semiconductor nanocrystals--can dramatically increase the efficiency of converting sunlight to electricity.

2010-06-01T23:59:59.000Z

105

BSA 11-04: Stepwise Surface Assembly of Quantum Dot-Fullerene ...  

Benefits. This procedure allows the preparation of high-purity solutions of quantum dot-fullerene heterodimers for use in photoelectric devices or for ...

106

Cellular Effect of High Doses of Silica-Coated Quantum Dot ...  

Cellular Effect of High Doses of Silica-Coated Quantum Dot Profiled with High Throughput Gene Expression Analysis and High Content Cellomics ...

107

A Graphene Quantum Dot with a Single Electron Transistor as Integrated Charge Sensor  

E-Print Network (OSTI)

We have developed an etching process to fabricate a quantum dot and a nearby single electron transistor as a charge detector in a single layer graphene. The high charge sensitivity of the detector is used to probe Coulomb diamonds as well as excited spectrum in the dot, even in the regime where the current through the quantum dot is too small to be measured by conventional transport means. The graphene based quantum dot and integrated charge sensor serve as an essential building block to form a solid-state qubit in a nuclear-spin-free quantum world.

Ling-Jun Wang; Gang Cao; Tao Tu; Hai-Ou Li; Cheng Zhou; Xiao-Jie Hao; Zhan Su; Guang-Can Guo; Guo-Ping Guo; Hong-Wen Jiang

2010-08-28T23:59:59.000Z

108

Optical Nonlinearities and Ultrafast Carrier Dynamics in Semiconductor Quantum Dots  

SciTech Connect

Low-dimensional semiconductors have attracted great interest due to the potential for tailoring their linear and nonlinear optical properties over a wide-range. Semiconductor nanocrystals (NC's) represent a class of quasi-zero-dimensional objects or quantum dots. Due to quantum cordhement and a large surface-to-volume ratio, the linear and nonlinear optical properties, and the carrier dynamics in NC's are significantly different horn those in bulk materials. napping at surface states can lead to a fast depopulation of quantized states, accompanied by charge separation and generation of local fields which significantly modifies the nonlinear optical response in NC's. 3D carrier confinement also has a drastic effect on the energy relaxation dynamics. In strongly confined NC's, the energy-level spacing can greatly exceed typical phonon energies. This has been expected to significantly inhibit phonon-related mechanisms for energy losses, an effect referred to as a phonon bottleneck. It has been suggested recently that the phonon bottleneck in 3D-confined systems can be removed due to enhanced role of Auger-type interactions. In this paper we report femtosecond (fs) studies of ultrafast optical nonlinearities, and energy relaxation and trap ping dynamics in three types of quantum-dot systems: semiconductor NC/glass composites made by high temperature precipitation, ion-implanted NC's, and colloidal NC'S. Comparison of ultrafast data for different samples allows us to separate effects being intrinsic to quantum dots from those related to lattice imperfections and interface properties.

Klimov, V.; McBranch, D.; Schwarz, C.

1998-08-10T23:59:59.000Z

109

Quantum Dot Solar Cells with Multiple Exciton Generation  

DOE Green Energy (OSTI)

We have measured the quantum yield of the multiple exciton generation (MEG) process in quantum dots (QDs) of the lead-salt semiconductor family (PbSe, PbTe, and PbS) using fs pump-probe transient absorption measurements. Very high quantum yields (up to 300%) for charge carrier generation from MEG have been measured in all of the Pb-VI QDs. We have calculated the potential maximum performance of various MEG QD solar cells in the detailed balance limit. We examined a two-cell tandem PV device with singlet fission (SF), QD, and normal dye (N) absorbers in the nine possible series-connected combinations to compare the tandem combinations and identify the combinations with the highest theoretical efficiency. We also calculated the maximum efficiency of an idealized single-gap MEG QD solar cell with M multiplications and its performance under solar concentration.

Hanna, M. C.; Beard, M. C.; Johnson, J. C.; Murphy, J.; Ellingson, R. J.; Nozik, A. J.

2005-11-01T23:59:59.000Z

110

Probing the size and environment induced phase transformation in CdSe quantum dots  

SciTech Connect

The structural and electronic properties of CdSe quantum dots in toluene and drop-casted on Si wafer were investigated by in-situ micro X-ray diffraction, X-ray photoelectron spectroscopy and UV-Vis absorption and emission spectroscopy. The in-situ micro diffraction data show that the CdSe quantum dots capped with TOPO or hexadecylamine (HDA) in toluene exhibit predominantly wurtzite crystal structure, which undergoes a phase transformation to zinc blende crystal structure following drop casting on Si and this phase transition increases with decreasing the size of the CdSe quantum dots. Decreasing the size of quantum dots also increases the Se vacancies that facilitate the phase transformation. The X-ray photoelectron spectra show a systematic increase in the core level binding energies of Cd 3d and Se 3d, the band gap and the Cd/Se ratio as the size of the quantum dots decreases from 6.6nm to 2.1nm. This is attributed to the quantum confinement of CdSe crystallites by the capping ligands in toluene which increases with decreasing the size of the quantum dots. However, drop-casting quantum dots on Si alter the density and arrangement of capping ligands and solvent molecules on the quantum dots which causes significant phase transformation.

Karakoti, Ajay S.; Sanghavi, Shail P.; Nachimuthu, Ponnusamy; Yang, Ping; Thevuthasan, Suntharampillai

2011-11-17T23:59:59.000Z

111

Compact biocompatible quantum dots via RAFT-mediated synthesis of imidazole-based random copolymer ligand  

E-Print Network (OSTI)

We present a new class of polymeric ligands for quantum dot (QD) water solubilization to yield biocompatible and derivatizable QDs with compact size (10?12 nm diameter), high quantum yields (>50%), excellent stability ...

Liu, Wenhao

112

The use of bulk states to accelerate the band edge state calculation of a semiconductor quantum dot  

E-Print Network (OSTI)

conduction band. For large CdSe quantum dots, the number ofidate our approach on both CdSe bulk systems and colloidala physical point of view, CdSe quantum dots are one of the

Vomel, Christof; Tomov, Stanimire Z.; Wang, Lin-Wang; Marques, Osni A.; Dongarra, Jack J.

2008-01-01T23:59:59.000Z

113

Multiscale Models of Quantum Dot Based Nanomaterials and Nanodevices for Solar Cells  

Science Conference Proceedings (OSTI)

NASA future exploration missions and space electronic equipment require improvements in solar cell efficiency and radiation hardness. Novel nano-engineered materials and quantum-dot (QD) based photovoltaic devices promise to deliver more efficient, lightweight, ... Keywords: Nanostructured solar cell, computer-aided design, drift-diffusion, hydrodynamics, intermediate band solar cells, multiscale, nanostructures, photovoltaic, quantum dot

Alexander I. Fedoseyev; Marek Turowski; Ashok Raman; Qinghui Shao; Alexander A. Balandin

2008-06-01T23:59:59.000Z

114

Multipartite electronic entanglement purification using quantum-dot spin and microcavity system  

Science Conference Proceedings (OSTI)

This paper presents an entanglement purification protocol of multipartite electronic spin entangled state resorting to quantum-dot (QD) spin and micro cavity coupled system. The QD and microcavity coupling system is used to construct parity check detectors ... Keywords: Entanglement purification, Multipartite, Quantum-dot and cavity

Chuan Wang; Ru Zhang; Yong Zhang; Hai-Qiang Ma

2013-01-01T23:59:59.000Z

115

Influence of Surfactants and Charges on CdSe Quantum Dots  

Science Conference Proceedings (OSTI)

The chemistry between CdSe quantum dots and common surface capping ligands is invested using density functional theory. We will discuss the electronic structures and optical properties of CdSe QDs controlled by the size of particle, self-organization, capping ligands, and positive charges. Charges on quantum dots have profound effects on their structures, binding energies, and optical properties.

Yang, Ping; Tretiak, Sergei; Ivanov, Sergei

2011-07-11T23:59:59.000Z

116

Non-delta-function electronic spectral densities in individual quantum dots  

Science Conference Proceedings (OSTI)

Using a simplified model approach we estimate the optical line shape of the transition lines observable in photoluminescence experiments on quantum dots. We use the theory based on the interaction of electrons with the longitudinal optical phonons only. ... Keywords: 73.21.La, 73.63.Kv, 78.67.Hc, Electron-phonon coupling, Luminescence, Quantum dots

Karel Král

2008-03-01T23:59:59.000Z

117

Photoluminescence beyond 1.5µm from InAs quantum dots  

Science Conference Proceedings (OSTI)

Photoluminescence measurements were carried out to investigate the origin of long wavelength emissions (~1.6@mm at room temperature) observed from wafers with InAs quantum dots capped with GaAsSb layers. For wafers with high Sb content (22% and 26%) ... Keywords: Photoluminescence, Quantum dots, Type-II

J. S. Ng; H. Y. Liu; M. J. Steer; M. Hopkinson; J. P. R. David

2006-12-01T23:59:59.000Z

118

Water-soluble luminescent quantum dots and biomolecular conjugates thereof and related compositions and method of use  

DOE Patents (OSTI)

The present invention provides a water-soluble luminescent quantum dot, a biomolecular conjugate thereof and a composition comprising such a quantum dot or conjugate. Additionally, the present invention provides a method of obtaining a luminescent quantum dot, a method of making a biomolecular conjugate thereof, and methods of using a biomolecular conjugate for ultrasensitive nonisotopic detection in vitro and in vivo.

Nie, Shuming (Bloomington, IN); Chan, Warren C. W. (Bloomington, IN); Emory, Steven R. (Los Alamos, NM)

2002-01-01T23:59:59.000Z

119

Hole-induced Dynamic Nuclear Polarization in Quantum Dots  

E-Print Network (OSTI)

We present a microscopic theory showing that an optically excited heavy hole can induce a steady-state nuclear polarization in a quantum dot. With the preferential direction of the nuclear spin flip set by the energy mismatch instead of thermal relaxation, the resulting nuclear polarization shows a sign dependence on the product of the nuclear Zeeman splitting and the frequency detuning of the pumping laser, leading to experimentally observed bidirectional hysteretic locking or shift of the optical absorption peak, accompanied by a significant suppression of the nuclear fluctuation and hence prolonged electron spin coherence time.

Yang, Wen

2010-01-01T23:59:59.000Z

120

Photoluminescence-enhanced biocompatible quantum dots by phospholipid functionalization  

SciTech Connect

A simple two-step strategy using phospholipid (PPL) to functionalize core/shell CdSe/ZnS quantum dots (QDs) has been described. The experimental data show that the use of S-H terminated PPL results not only in the high colloidal stability of core/shell CdSe/ZnS QDs in the aqueous phase, but also in the significant enhancement of photoluminescence. The degree of the enhancement is a function of the PPL-CdSe/ZnS QDs sample concentration. These results might be promising for future biological platform in new devices ranging from photovoltaic cells to biosensors and other devices.

Shi Yunfeng [School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); He Peng [Department of Chemistry, North Carolina State University, Raleigh, NC 27695 (United States)], E-mail: phe@ncsu.edu; Zhu Xinyuan [School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Instrumental Analysis Center, Shanghai Jiao Tong University, 1954 Huashan Road, Shanghai 200030 (China)], E-mail: xyzhu@sjtu.edu.cn

2008-10-02T23:59:59.000Z

Note: This page contains sample records for the topic "quantum dot tracers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

Full Counting Statistics of Photons Emitted by Double Quantum Dot  

E-Print Network (OSTI)

We analyze the full counting statistics of photons emitted by a double quantum dot (DQD) to a high-quality microwave transmission line due to the dipole coupling. We show that at the resonant condition between the energy splitting of the DQD and the photon energy in the transmission line, photon statistics exhibits both a sub-Poissonian distribution and antibunching. In the ideal case, when the system decoherence stems only from photodetection, the photon noise is reduced below one-half of the noise for the Poisson distribution. The photon distribution remains sub-Poissonian even at moderate decoherence in the DQD.

Canran Xu; Maxim G. Vavilov

2013-03-27T23:59:59.000Z

122

Activation of molecular catalysts using semiconductor quantum dots  

DOE Patents (OSTI)

Photocatalytic materials based on coupling of semiconductor nanocrystalline quantum dots (NQD) and molecular catalysts. These materials have capability to drive or catalyze non-spontaneous chemical reactions in the presence of visible radiation, ultraviolet radiation, or both. The NQD functions in these materials as a light absorber and charge generator. Following light absorption, the NQD activates a molecular catalyst adsorbed on the surface of the NQD via transfer of one or more charges (either electrons or electron-holes) from the NQD to the molecular catalyst. The activated molecular catalyst can then drive a chemical reaction. A photoelectrolytic device that includes such photocatalytic materials is also described.

Meyer, Thomas J. (Chapel Hill, NC); Sykora, Milan (Los Alamos, NM); Klimov, Victor I. (Los Alamos, NM)

2011-10-04T23:59:59.000Z

123

Photoluminescence Blinking Dynamics of Colloidal Quantum Dots in the Presence of Controlled External Electron Traps  

Science Conference Proceedings (OSTI)

The effect of the external charge trap on the photoluminescence blinking dynamics of individual colloidal quantum dots is investigated with a series of colloidal quantum dot-bridge-fullerene dimers with varying bridge lengths, where the fullerene moiety acts as a well-defined, well-positioned external charge trap. It is found that charge transfer followed by charge recombination is an important mechanism in determining the blinking behavior of quantum dots when the external trap is properly coupled with the excited state of the quantum dot, leading to a quasi-continuous distribution of 'on' states and an early fall-off from a power-law distribution for both 'on' and 'off' times associated with quantum dot photoluminescence blinking.

Cotlet, M.; Xu, Z.

2012-01-23T23:59:59.000Z

124

Intermediate-band photosensitive device with quantum dots embedded in energy fence barrier  

DOE Patents (OSTI)

A plurality of layers of a first semiconductor material and a plurality of dots-in-a-fence barriers disposed in a stack between a first electrode and a second electrode. Each dots-in-a-fence barrier consists essentially of a plurality of quantum dots of a second semiconductor material embedded between and in direct contact with two layers of a third semiconductor material. Wave functions of the quantum dots overlap as at least one intermediate band. The layers of the third semiconductor material are arranged as tunneling barriers to require a first electron and/or a first hole in a layer of the first material to perform quantum mechanical tunneling to reach the second material within a respective quantum dot, and to require a second electron and/or a second hole in a layer of the first semiconductor material to perform quantum mechanical tunneling to reach another layer of the first semiconductor material.

Forrest, Stephen R. (Ann Arbor, MI); Wei, Guodan (Ann Arbor, MI)

2010-07-06T23:59:59.000Z

125

Adiabatic quantum state transfer in non-uniform triple-quantum-dot system  

E-Print Network (OSTI)

We introduce an adiabatic quantum state transfer scheme in a non-uniform coupled triple-quantum-dot system. By adiabatically varying the external gate voltage applied on the sender and receiver, the electron can be transferred between them with high fidelity. By numerically solving the master equation for a system with always-on interaction, it is indicated that the transfer fidelity depends on the ration between the peak voltage and the maximum coupling constants. The effect of coupling mismatch on the transfer fidelity is also investigated and it is shown that there is a relatively large tolerance range to permit high fidelity quantum state transfer.

Bing Chen; Wei Fan; Yan Xu

2010-10-18T23:59:59.000Z

126

Theory of Electro-optic Modulation via a Quantum Dot Coupled to a Nano-resonator  

E-Print Network (OSTI)

In this paper, we analyze the performance of an electro-optic modulator based on a single quantum dot strongly coupled to a nano-resonator, where electrical control of the quantum dot frequency is achieved via quantum confined Stark effect. Using realistic system parameters, we show that modulation speeds of a few tens of GHz are achievable with this system, while the energy per switching operation can be as small as 0.5 fJ. In addition, we study the non-linear distortion, and the effect of pure quantum dot dephasing on the performance of the modulator.

Arka Majumdar; Nicolas Manquest; Andrei Faraon; Jelena Vuckovic

2009-11-27T23:59:59.000Z

127

Ionisation of a quantum dot by electric fields  

Science Conference Proceedings (OSTI)

We have derived analytical formulas for differential and total ionisation probabilities of a two-dimensional quantum dot by a constant electric field. In the adiabatic approximation, we have calculated the probability of this process in the field of a plane electromagnetic wave and in a superposition of constant and alternating electric fields. The imaginary-time method is used to obtain the momentum distribution of the ionisation probability of a bound system by an intense field generated by a superposition of parallel constant and alternating electric fields. The total probability of the process per unit time is calculated with exponential accuracy. The dependence of the results obtained on the characteristic parameters of the problem is investigated. (laser applications and other topics in quantum electronics)

Eminov, P A; Gordeeva, S V

2012-08-31T23:59:59.000Z

128

GaAs structures with InAs and As quantum dots produced in a single molecular beam epitaxy process  

Science Conference Proceedings (OSTI)

Epitaxial GaAs layers containing InAs semiconductor quantum dots and As metal quantum dots are grown by molecular beam epitaxy. The InAs quantum dots are formed by the Stranskii-Krastanow mechanism, whereas the As quantum dots are self-assembled in the GaAs layer grown at low temperature with a large As excess. The microstructure of the samples is studied by transmission electron microscopy. It is established that the As metal quantum dots formed in the immediate vicinity of the InAs semiconductor quantum dots are larger in size than the As quantum dots formed far from the InAs quantum dots. This is apparently due to the effect of strain fields of the InAs quantum dots upon the self-assembling of As quantum dots. Another phenomenon apparently associated with local strains around the InAs quantum dots is the formation of V-like defects (stacking faults) during the overgrowth of the InAs quantum dots with the GaAs layer by low-temperature molecular beam epitaxy. Such defects have a profound effect on the self-assembling of As quantum dots. Specifically, on high-temperature annealing needed for the formation of large-sized As quantum dots by Ostwald ripening, the V-like defects bring about the dissolution of the As quantum dots in the vicinity of the defects. In this case, excess arsenic most probably diffuses towards the open surface of the sample via the channels of accelerated diffusion in the planes of stacking faults.

Nevedomskii, V. N., E-mail: nevedom@mail.ioffe.ru; Bert, N. A.; Chaldyshev, V. V., E-mail: Chald@gvg.ioffe.ru [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation); Preobrazhenskii, V. V.; Putyato, M. A.; Semyagin, B. R. [Russian Academy of Sciences, Institute of Semiconductor Physics, Siberian Division (Russian Federation)

2009-12-15T23:59:59.000Z

129

Analysis of mechanisms of carrier emission in the p-i-n structures with In(Ga)As quantum dots  

SciTech Connect

With the help of the photocurrent spectroscopy, the mechanism of emission of charge carriers from energy levels of the (In,Ga)As/(Al,Ga)As quantum dots of different design are studied. Thermal activation is shown to be the main mechanism of carrier emission from the quantum dots for the isolated layer of quantum dots separated by wide (Al,Ga)As spacer layers. At a small width of the (Al,Ga)As spacer layer, when electron binding of separate layers of the quantum dots in the vertical direction takes place, the role of the tunneling mechanism of carrier emission between the vertically coupled quantum dots increases.

Shatalina, E. S., E-mail: Shatalina@mail.ioffe.ru; Blokhin, S. A.; Nadtochy, A. M.; Payusov, A. S.; Savelyev, A. V.; Maximov, M. V.; Zhukov, A. E. [St. Petersburg Academic University, Nanotechnology Research and Education Centre (Russian Federation); Ledentsov, N. N. [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation); Kovsh, A. R.; Mikhrin, S. S.; Ustinov, V. M. [Innolume GmbH (Germany)

2010-10-15T23:59:59.000Z

130

Probing semiconductor quantum dot state and manipulation with superconducting transmission line resonator  

E-Print Network (OSTI)

A coupled system of a superconducting transmission line resonator with a semiconductor double quantum dot is analyzed. We simulate the phase shift of the microwave signal in the resonator, which is sensitive to the quantum dot qubit state and manipulation. The measurement quality is sufficiently high and the results demonstrate a solid-state quantum processor based on this type of circuit can be envisioned.

Zhe Guan

2013-12-08T23:59:59.000Z

131

Quantum computation with moving quantum dots generated by surface acoustic waves  

Science Conference Proceedings (OSTI)

Motivated by recent experimental observations [M. Kataoka et al., Phys. Rev. Lett. 102, 156801 (2009)], we propose here a theoretical approach to implement quantum computation with bound states of electrons in moving quantum dots generated by the driving of surface acoustic waves. Differing from static quantum dots defined by a series of static electrodes above the two-dimensional electron gas (2DEG), here a single electron is captured from a 2DEG reservoir by a surface acoustic wave and then trapped in a moving quantum dot (MQD) transported across a quasi-one-dimensional channel, wherein all the electrons have been excluded by the actions of the surface gates. The flying qubit introduced here is encoded by the two lowest levels of the electron in the MQD, and the Rabi oscillation between these two levels could be implemented by applying finely selected microwave pulses to the surface gates. By using the Coulomb interaction between the electrons in different MQDs, we show that a desirable two-qubit operation, i.e., iswap gate, could be realized. Readouts of the present flying qubits are also feasible with the current single-electron detected technique.

Shi, X.; Zhang, M. [Quantum Optoelectronics Laboratory, School of Physics and Technology, Southwest Jiaotong University, Chengdu 610031 (China); Wei, L. F. [Quantum Optoelectronics Laboratory, School of Physics and Technology, Southwest Jiaotong University, Chengdu 610031 (China); State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics Science and Engineering, Sun Yet-sen University, Guangzhou 510275 (China)

2011-12-15T23:59:59.000Z

132

Tuning the properties of Ge-quantum dots superlattices in amorphous silica matrix through deposition conditions  

Science Conference Proceedings (OSTI)

In this work, we investigate the structural properties of Ge quantum dot lattices in amorphous silica matrix, prepared by low-temperature magnetron sputtering deposition of (Ge+SiO{sub 2})/SiO{sub 2} multilayers. The dependence of quantum dot shape, size, separation, and arrangement type on the Ge-rich (Ge + SiO{sub 2}) layer thickness is studied. We show that the quantum dots are elongated along the growth direction, perpendicular to the multilayer surface. The size of the quantum dots and their separation along the growth direction can be tuned by changing the Ge-rich layer thickness. The average value of the quantum dots size along the lateral (in-plane) direction along with their lateral separation is not affected by the thickness of the Ge-rich layer. However, the thickness of the Ge-rich layer significantly affects the quantum dot ordering. In addition, we investigate the dependence of the multilayer average atomic composition and also the quantum dot crystalline quality on the deposition parameters.

Pinto, S. R. C.; Ramos, M. M. D.; Gomes, M. J. M. [University of Minho, Centre of Physics and Physics Department, Braga 4710-057 (Portugal); Buljan, M. [Ruder Boskovic Institute, Bijenicka cesta 54, Zagreb 10000 (Croatia); Chahboun, A. [University of Minho, Centre of Physics and Physics Department, Braga 4710-057 (Portugal); Physics Department, FST Tanger, Tanger BP 416 (Morocco); Roldan, M. A.; Molina, S. I. [Departamento de Ciencia de los Materiales e Ing. Metalurgica y Q. I., Universidad de Cadiz, Cadiz (Spain); Bernstorff, S. [Sincrotrone Trieste, SS 14 km163, 5, Basovizza 34012 (Italy); Varela, M.; Pennycook, S. J. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Barradas, N. P.; Alves, E. [Instituto Superior Tecnico e Instituto Tecnologico e Nuclear-, EN10, Sacavem 2686-953 (Portugal)

2012-04-01T23:59:59.000Z

133

Tuning the properties of Ge-quantum dots superlattices in amorphous silica matrix through deposition conditions  

Science Conference Proceedings (OSTI)

In this work, we investigate the structural properties of Ge quantum dot lattices in amorphous silica matrix, prepared by low-temperature magnetron sputtering deposition of (Ge+SiO{sub 2})/SiO{sub 2} multilayers. The dependence of quantum dot shape, size, separation, and arrangement type on the Ge-rich (Ge + SiO{sub 2}) layer thickness is studied. We show that the quantum dots are elongated along the growth direction, perpendicular to the multilayer surface. The size of the quantum dots and their separation along the growth direction can be tuned by changing the Ge-rich layer thickness. The average value of the quantum dots size along the lateral (in-plane) direction along with their lateral separation is not affected by the thickness of the Ge-rich layer. However, the thickness of the Ge-rich layer significantly affects the quantum dot ordering. In addition, we investigate the dependence of the multilayer average atomic composition and also the quantum dot crystalline quality on the deposition parameters.

Pinto, S. [University of Minho, Portugal; Roldan Gutierrez, Manuel A [ORNL; Ramos, M. M.D. [University of Minho, Portugal; Gomes, M.J.M. [University of Minho, Portugal; Molina, S. I. [Universidad de Cadiz, Spain; Pennycook, Stephen J [ORNL; Varela del Arco, Maria [ORNL; Buljan, M. [R. Boskovic Institute, Zagreb, Croatia; Barradas, N. [Instituto Tecnologico e Nuclear (ITN), Lisbon, Portugal; Alves, E. [Instituto Tecnologico e Nuclear (ITN), Lisbon, Portugal; Chahboun, A. [FST Tanger, Morocco; Bernstorff, S. [Sincrotrone Trieste, Basovizza, Italy

2012-01-01T23:59:59.000Z

134

Excitonic enhancement of nonradiative energy transfer from a quantum well in the optical near field of energy gradient quantum dots  

E-Print Network (OSTI)

Excitonic enhancement of nonradiative energy transfer from a quantum well in the optical near field of energy gradient quantum dots Sedat Nizamoglu, Pedro Ludwig Hernández-Martínez, Evren Mutlugun, Durmus misfit strains on the band offsets of Zn1-xBexO/ZnO quantum wells: A first-principles analysis J. Appl

Demir, Hilmi Volkan

135

Approaches to Future Generation Photovoltaics and Solar Fuels: Multiple Exciton Generation in Quantum Dots, Quantum Dot Arrays, Molecular Singlet Fission, and Quantum Dot Solar Cells  

DOE Green Energy (OSTI)

One potential, long-term approach to more efficient future generation solar cells is to utilize the unique properties of quantum dots (QDs) and unique molecular chromophores to control the relaxation pathways of excited states to produce enhanced conversion efficiency through efficient multiple electron-hole pair generation from single photons . We have observed efficient multiple exciton generation (MEG) in PbSe, PbS, PbTe, and Si QDs and efficient singlet fission (SF) in molecules that satisfy specific requirements for their excited state energy level structure to achieve carrier multiplication. We have studied MEG in close-packed QD arrays where the QDs are electronically coupled in the films and thus exhibit good transport while still maintaining quantization and MEG. We have developed simple, all-inorganic QD solar cells that produce large short-circuit photocurrents and power conversion efficiencies in the 3-5% range via both nanocrystalline Schottky junctions and nanocrystalline p-n junctions. These solar cells also show QYs for photocurrent that exceed 100% in the photon energy regions where MEG is possible; the photocurrent MEG QYs as a function of photon energy match those determined via time-resolved spectroscopy. We have also observed very efficient SF in thin films of molecular crystals of 1,3 diphenylisobenzofuran with quantum yields of 200% at the optimum SF threshold of 2Eg (HOMO-LUMO for S{sub 0}-S{sub 1}), reflecting the creation of two excited triplet states from the first excited singlet state. Various possible configurations for novel solar cells based on MEG in QDs and SF in molecules that could produce high conversion efficiencies will be presented, along with progress in developing such new types of solar cells. Recent analyses of the effect of MEG or SF combined with solar concentration on the conversion efficiency of solar cells will be discussed.

Nozik, A. J.; Beard, M. C.; Johnson, J. C.; Hanna, M. C.; Luther, J. M.; Midgett, A.; Semonin, O.; Michel, J.

2012-01-01T23:59:59.000Z

136

Polaron effect-dependent third-order optical susceptibility in a ZnS/CdSe quantum dot quantum well  

Science Conference Proceedings (OSTI)

The effect of the electron-phonon interaction on the third-harmonic is investigated theoretically for electrons confined in a core-shell quantum dot. The interactions of electrons with different phonon modes in the core-shell system, including the confined ... Keywords: 42.65.An, 71.38.-k, 78.67.Hc, Core-shell quantum dot, Nonlinear optical susceptibility, Polarons

Zhihong Chen; Duanzheng Yao; Xi Zhang; Tianhong Fang

2008-12-01T23:59:59.000Z

137

Self-organized lattice of ordered quantum dot molecules  

SciTech Connect

Ordered groups of InAs quantum dots (QDs), lateral QD molecules, are created by self-organized anisotropic strain engineering of a (In,Ga)As/GaAs superlattice (SL) template on GaAs (311)B in molecular-beam epitaxy. During stacking, the SL template self-organizes into a two-dimensionally ordered strain modulated network on a mesoscopic length scale. InAs QDs preferentially grow on top of the nodes of the network due to local strain recognition. The QDs form a lattice of separated groups of closely spaced ordered QDs whose number can be controlled by the GaAs separation layer thickness on top of the SL template. The QD groups exhibit excellent optical properties up to room temperature.

Lippen, T. von; Noetzel, R.; Hamhuis, G.J.; Wolter, J.H. [eiTT/COBRA Inter-University Research Institute, Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands)

2004-07-05T23:59:59.000Z

138

Full Counting Statistics of Photons Emitted by Double Quantum Dot  

E-Print Network (OSTI)

We analyze the full counting statistics of photons emitted by a double quantum dot (DQD) coupled to a high-quality microwave resonator by electric dipole interaction. We show that at the resonant condition between the energy splitting of the DQD and the photon energy in the resonator, photon statistics exhibits both a sub-Poissonian distribution and antibunching. In the ideal case, when the system decoherence stems only from photodetection, the photon noise is reduced below one-half of the noise for the Poisson distribution and is consistent with current noise. The photon distribution remains sub-Poissonian even at moderate decoherence in the DQD. We demonstrate that Josephson junction based photomultipliers can be used to experimentally assess statistics of emitted photons.

Canran Xu; Maxim G. Vavilov

2013-03-27T23:59:59.000Z

139

Solid-state photonic interfaces using semiconductor quantum dots  

E-Print Network (OSTI)

. Boyer de la Giroday, N. Sko¨ld, I. Farrer, C.A. Nicoll, D.A. Ritchie, and A.J. Shields Nature Physics, 6, 947 (2010) 3. All-electrical coherent control of the exciton states in a single quantum dot A. Boyer de la Giroday, A.J. Bennett, M.A. Pooley, R... O. Thomas, C.L. Salter, A.J. Bennett, R.M. Stevenson, M.A. Pooley, M.B. Ward, R.B. Patel, A. Boyer de la Giroday, N. Sko¨ld, I. Far- rer, C.A. Nicoll, D.A. Ritchie, and A.J. Shields Proc. QCMC 2010 2. Observation of anticrossings in the exciton state...

Boyer de la Giroday, Antoine

2012-02-07T23:59:59.000Z

140

Resonant Spectroscopy of II-VI Self-Assembled Quantum Dots: Excited States and Exciton-LO Phonon Coupling  

E-Print Network (OSTI)

Using resonantly excited photoluminescence along with photoluminescence excitation spectroscopies, we study the carrier excitation processes in CdTe/ZnTe and CdSe/ZnSe self-assembled quantum dots. Photoluminescence excitation spectra of single CdTe quantum dots reflect two major mechanisms for carrier excitation: The first, associated with the presence of sharp and intense lines in the spectrum, is a direct excited state ? ground state transition. The second, associated with the appearance of up to four much broader excitation lines, is a LO phonon-assisted absorption directly into the quantum dot ground states. LO phonons with energies of both quantum dots and ZnTe barrier material are identified in the photoluminescence excitation spectra. Resonantly excited PL measurements for the dot ensemble as a function of excitation energy makes it possible to separate the contributions of these two mechanisms. We find that for CdTe quantum dots the distribution of excited states coupled to the ground states reflects the energy distribution of the quantum dot emission, but shifted up in energy by 100 meV. This large splitting between excited and ground states in CdTe quantum dots suggests strong spatial confinement. In contrast, the LO phonon-assisted absorption shows significant size selectivity. In the case of CdTe dots the exciton-LO phonon coupling is strongly enhanced for smaller-sized dots which have higher emission energies. In contrast, for CdSe quantum dots the exciton-LO phonon coupling is uniform over the ensemble ? that is, the energy distribution determines the intensities of LO phonon replicas. We show that for CdTe quantum dots after annealing, that is after an increase in the average dot size, the exciton-LO phonon interaction reflects the dot energy distribution, as observed for CdSe quantum dots.

T. A. Nguyen; S. Mackowski; H. E. Jackson; L. M. Smith; J. Wrobel; K. Fronc; G. Karczewski; J. Kossut; M. Dobrowolska J. K. Furdyna; W. Heiss

2003-09-17T23:59:59.000Z

Note: This page contains sample records for the topic "quantum dot tracers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

Argonne CNM Highlight: Coupling of Single Quantum Dots to Smooth Metal  

NLE Websites -- All DOE Office Websites (Extended Search)

Coupling of Single Quantum Dots to Smooth Metal Films Single Quantum Dots Coupledl to Smooth Metal Films ArtistÂąs rendition of semiconductor nanocrystals near a gold film. The metal increases nanocrystal emission rates depending on their orientation. [selected as cover image for Phys. Chem. Chem. Phys., 11, 5853 (2009)] Staff in the CNM Nanophotonics Group have measured how light emission from individual colloidal semiconductor nanocrystals, or quantum dots, is modified when in proximity to smooth metal films. Metal nanostructures can strongly modify how quantum dots emit light because of their coupling to electron oscillations in the metal, known as surface plasmons. Emission modification is important for the improvement of light-emitting devices,

142

Electrical excitation of colloidally synthesized quantum dots in metal oxide structures  

E-Print Network (OSTI)

This thesis develops methods for integrating colloidally synthesized quantum dots (QDs) and metal oxides in optoelectronic devices, presents three distinct light emitting devices (LEDs) with metal oxides surrounding a QD ...

Wood, Vanessa Claire

2010-01-01T23:59:59.000Z

143

Optimization of a microwave resonator cavity to perform electron spin resonance measurements on quantum dots  

E-Print Network (OSTI)

This thesis attempts to improve on an ongoing experiment of detecting electron spin resonance (ESR) on AlGaAs/GaAs lateral quantum dots. The experiment is performed in a 2.5 Tesla magnetic field at temperatures around ...

Burger, Anat

2006-01-01T23:59:59.000Z

144

The physics and chemistry of transport in CdSe quantum dot solids  

E-Print Network (OSTI)

Semiconductor quantum dots (QDs) have tunable opto-electronic properties and can be chemically synthesized and manipulated with ease, making them a promising novel material for many diverse applications. An understanding ...

Jarosz, Mirna, 1981-

2004-01-01T23:59:59.000Z

145

Luminescent, quantum dot-based anti-reflective coatings for crystalline silicon photovoltaics  

E-Print Network (OSTI)

This thesis demonstrates and evaluates the potential application of luminescent quantum dot/polymer solutions on crystalline silicon photovoltaics. After spin coating the QD/polymer onto silicon photodiodes, an increase ...

Bruer, Garrett (Garrett A.)

2010-01-01T23:59:59.000Z

146

Quantum Dots Promise to Significantly Boost Solar Cell Efficiencies (Fact Sheet)  

DOE Green Energy (OSTI)

In the search for a third generation of solar-cell technologies, a leading candidate is the use of 'quantum dots' -- tiny spheres of semiconductor material measuring only about 2-10 billionths of a meter in diameter. Quantum dots have the potential to dramatically increase the efficiency of converting sunlight into energy -- perhaps even doubling it in some devices -- because of their ability to generate more than one bound electron-hole pair, or exciton, per incoming photon. NREL has produced quantum dots using colloidal suspensions; then, using molecular self-assembly, they have been fabricated into the first-ever quantum-dot solar cells. While these devices operate with only 4.4% efficiency, they demonstrate the capability for low-cost manufacturing.

Not Available

2013-08-01T23:59:59.000Z

147

Photoacoustic study of CdS QDs for application in quantum-dot-sensitized solar cells  

Science Conference Proceedings (OSTI)

The optical properties and photovoltaic characterization of CdS quantum dots sensitized solar cells (QDSSCs) were studied. CdS QDs were prepared by the chemical solution deposition (CD) technique. Photoacoustic spectroscopy (PA) was employed to study ...

S. Abdallah, N. Al-Hosiny, Ali Badawi

2012-01-01T23:59:59.000Z

148

Structural Origin of Enhanced Luminescence Efficiency of Antimony Irradiated InAs Quantum Dots  

Science Conference Proceedings (OSTI)

We report that Sb irradiation combined with the presence of a GaAs intermediate layer previous to the deposition of a GaSb layer over InAs quantum dots grown by molecular beam epitaxy improves the crystalline quality of these nanostructures. Moreover, this approach to develop III-V-Sb nanostructures causes the formation of quantum dots buried by a confining GaSb layer and, in this way, achieving a type II band alignment. Both phenomena, studied by Conventional transmission electron microscopy (CTEM) and scanning-transmission electron microscope (STEM) techniques are keys to achieve the best room temperature photoluminescence results from InAs/GaAs (001) quantum dots. The Sb flux contributes to the preservation of the quantum dots size and at the same time reduces In diffusion from the wetting layer.

Beltran, AM [Universidad de Cadiz, Spain; Ben, Teresa [Universidad de Cadiz, Spain; Sales, David [Universidad de Cadiz, Spain; Sanchez, AM [University of Warwick, UK; Ripalda, JM [Instituto de Microelectronica de Madrid (CNM, CSIC); Taboada, Alfonso G [Instituto de Microelectronica de Madrid (CNM, CSIC); Varela del Arco, Maria [ORNL; Pennycook, Stephen J [ORNL; Molina, S. I. [Universidad de Cadiz, Spain

2011-01-01T23:59:59.000Z

149

Mechanistic Insights into the Formation of InP Quantum Dots  

E-Print Network (OSTI)

The molecular mechanism of InP colloidal quantum dot (QD) syntheses was investigated by NMR spectroscopy. Unlike methods for monodisperse PbSe and CdSe, existing InP syntheses result in total depletion of molecular phosphorous ...

Allen, Peter?M.

150

Developing quantum dot phosphor-based light-emitting diodes for aviation lighting applications  

Science Conference Proceedings (OSTI)

We have investigated the feasibility of employing quantum dot (QD) phosphor-based light-emitting diodes (LEDs) in aviation applications that request Night Vision Imaging Systems (NVIS) compliance. Our studies suggest that the emerging QD phosphorbased ...

Fengbing Wu; Dawei Zhang; Shuzhen Shang; Yiming Zhu; Songlin Zhuang; Jian Xu

2012-01-01T23:59:59.000Z

151

Preparation of DNA-Functionalised CdSe/ZnS Quantum Dots  

E-Print Network (OSTI)

We functionalised core-shell CdSe/ZnS quantum dots (QDots) with short-chain 3-mercaptopropionic acid (3MPA) to render these nanocrystalline semiconductor water-soluble. The ligand-exchange reaction was significantly improved ...

Pong, Boon Kin

152

Characterization of peptide-mediated delivery of quantum dots into cortical astrocytes  

E-Print Network (OSTI)

F. Jensen, and M. G. Bawendi. (cdse)zns core-shell quantumof highly luminescent cdse/ cds core/shell nanocrystals withproteins or peptides and cdse-zns quantum dots. Journal of

Nguyen-Ta, Kim Thanh

2011-01-01T23:59:59.000Z

153

Electroluminescense from InGaN Quantum Dots, in a Monolithically ...  

Science Conference Proceedings (OSTI)

We present an electrically driven structure based on a monolithically GaN/AlInN cavity with a single quantum dot layer grown by MOVPE. The device was grown ...

154

Efficiency loss mechanisms in colloidal quantum-dot light-emitting diodes  

E-Print Network (OSTI)

Saturated and tunable emission colors make colloidal quantum-dot light-emitting diodes (QD-LEDs) interesting for the next generation of display and lighting technologies. However, there still remain various hurdles to the ...

Shirasaki, Yasuhiro

2013-01-01T23:59:59.000Z

155

Coulomb Interaction between InAs/GaAs Quantum Dots and Adjacent Impurities  

Science Conference Proceedings (OSTI)

Defects positioned close to a plane of quantum dots (QDs) are shown to be influenced by coulomb interaction effect when the quantum dots are charged by electrons. Signals from deep level transient spectroscopy (DLTS) measurement give rise to a mirror effect in the spectrum depending on movement of the defect energy level in relation to the Fermi-level as a result of the electron traffic at the QDs.

Engstroem, O. [Institute of Electron Technology, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Chalmers University of Technology, Kemivaegen 9, SE-412 96, Goeteborg (Sweden); Kaniewska, M.; Kaczmarczyk, M. [Institute of Electron Technology, Al. Lotnikow 32/46, 02-668 Warsaw (Poland)

2011-12-23T23:59:59.000Z

156

Quantum Dot–Bridge–Fullerene Heterodimers with Controlled Photoinduced Electron Transfer  

Science Conference Proceedings (OSTI)

A series of donor-bridge-acceptor systems in the form of core/shell CdSe/ZnS quantum dot-bridge-fullerene heterodimers (see picture) with varying bridge length and varying quantum dot size were self-assembled by a surface-based stepwise method to demonstrate control of the rate and of the magnitude of fluctuations of photoinduced electron transfer at the single-molecule level.

Cotlet, M.; Xu, Z.

2011-06-27T23:59:59.000Z

157

Wavelength controlled InAs/InP quantum dots for telecom laser applications  

Science Conference Proceedings (OSTI)

This article reviews the recent progress in the growth and device applications of InAs/InP quantum dots (QDs) for telecom applications. Wavelength tuning of the metalorganic vapor-phase epitaxy grown single layer and stacked InAs QDs embedded in InGaAsP/InP ... Keywords: InAs, InGaAsP, InP (100), Laser, Metalorganic vapor-phase epitaxy, Quantum dot

S. Anantathanasarn; R. Nötzel; P. J. van Veldhoven; F. W. M. van Otten; Y. Barbarin; G. Servanton; T. de Vries; E. Smalbrugge; E. J. Geluk; T. J. Eijkemans; E. A. J. M. Bente; Y. S. Oei; M. K. Smit; J. H. Wolter

2006-12-01T23:59:59.000Z

158

Dephasing and Measurement Efficiency via a Quantum Dot Detector  

E-Print Network (OSTI)

We study charge detection and controlled dephasing of a mesoscopic system via a quantum dot detector (QDD), where the mesoscopic system and the QDD are capacitively coupled. The QDD is considered to have coherent resonant tunnelling via a single level. It is found that the dephasing rate is proportional to the square of the conductance of the QDD for the Breit-Wigner model, showing that the dephasing is completely different from the shot noise of the detector. The measurement rate, on the other hand, shows a dip near the resonance. Our findings are peculiar especially for a symmetric detector in the following aspect: The dephasing rate is maximum at resonance of the QDD where the detector conductance is insensitive to the charge state of the mesoscopic system. As a result, the efficiency of the detector shows a dip and vanishes at resonance, in contrast to the single-channel symmetric non-resonant detector that has always a maximum efficiency. We find that this difference originates from a very general property of the scattering matrix: The abrupt phase change exists in the scattering amplitudes in the presence of the symmetry, which is insensitive to the detector current but {\\em stores} the information of the quantum state of the mesoscopic system.

Gyong Luck Khym; Youngnae Lee; Kicheon Kang

2006-01-24T23:59:59.000Z

159

Quantum Dot Solar Cells: High Efficiency through Multiple Exciton Generation  

DOE Green Energy (OSTI)

Impact ionization is a process in which absorbed photons in semiconductors that are at least twice the bandgap can produce multiple electron-hole pairs. For single-bandgap photovoltaic devices, this effect produces greatly enhanced theoretical thermodynamic conversion efficiencies that range from 45-85%, depending upon solar concentration, the cell temperature, and the number of electron-hole pairs produced per photon. For quantum dots (QDs), electron-hole pairs exist as excitons. We have observed astoundingly efficient multiple exciton generation (MEG) in QDs of PbSe (bulk Eg = 0.28 eV), ranging in diameter from 3.9 to 5.7nm (Eg = 0.73, 0.82, and 0.91 eV, respectively). The effective masses of electron and holes are about equal in PbSe, and the onset for efficient MEG occurs at about three times the QD HOMO-LUMO transition (its ''bandgap''). The quantum yield rises quickly after the onset and reaches 300% at 4 x Eg (3.64 eV) for the smallest QD; this means that every QD in the sample produces three electron-hole pairs/photon.

Hanna, M. C.; Ellingson, R. J.; Beard, M.; Yu, P.; Micic, O. I.; Nozik, A. J.; c.

2005-01-01T23:59:59.000Z

160

Evolution of exciton states near the percolation threshold in two-phase systems with II-VI semiconductor quantum dots  

SciTech Connect

From studies of two-phase systems (borosilicate matrices containing ZnSe or CdS quantum dots), it was found that the systems exhibit a specific feature associated with the percolation phase transition of charge carriers (excitons). The transition manifests itself as radical changes in the optical spectra of both ZnSe and CdS quantum dot systems and by fluctuations of the emission band intensities near the percolation threshold. These effects are due to microscopic fluctuations of the density of quantum dots. The average spacing between quantum dots is calculated taking into account their finite dimensions and the volume fraction occupied by the quantum dots at the percolation threshold. It is shown that clustering of quantum dots occurs via tunneling of charge carriers between the dots. A physical mechanism responsible for the percolation threshold for charge carriers is suggested. In the mechanism, the permittivity mismatch of the materials of the matrix and quantum dots plays an important role in delocalization of charge carriers (excitons): due to the mismatch, 'a dielectric trap' is formed at the external surface of the interface between the matrix and a quantum dot and, thus, surface exciton states are formed there. The critical concentrations of quantum dots are determined, such that the spatial overlapping of such surface states provides the percolation transition in both systems.

Bondar, N. V., E-mail: jbond@iop.kiev.ua; Brodyn, M. S. [National Academy of Sciences of Ukraine, Institute of Physics (Ukraine)

2010-07-15T23:59:59.000Z

Note: This page contains sample records for the topic "quantum dot tracers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

Specific features of photoluminescence properties of copper-doped cadmium selenide quantum dots  

SciTech Connect

The effect of doping with copper on the photoluminescence properties of cadmium selenide quantum dots 4 nm in dimension is studied. The quenching of the excitonic photoluminescence band related to the quantum dots and the appearance of an impurity photoluminescence band in the near-infrared region are observed after doping of the quantum dots with copper. It is established that, on doping of the quantum dots, the photoluminescence kinetics undergoes substantial changes. The photoluminescence kinetics of the undoped quantum dots is adequately described by a sum of exponential relaxation relations, whereas the photoluminescence kinetics experimentally observed in the region of the impurity band of the copper-doped samples follows stretched exponential decay, with the average lifetimes 0.3-0.6 {mu}s at the photon energies in the range of 1.47-1.82 eV. The experimentally observed changes in the photoluminescence properties are attributed to transformation of radiative centers in the quantum dots when doped with copper atoms.

Tselikov, G. I., E-mail: gleb@vega.phys.msu.ru [Moscow State University, Faculty of Physics (Russian Federation); Dorofeev, S. G.; Tananaev, P. N. [Moscow State University, Faculty of Chemistry (Russian Federation); Timoshenko, V. Yu. [Moscow State University, Faculty of Physics (Russian Federation)

2011-09-15T23:59:59.000Z

162

Characteristics of quadratic electro-optic effects and electro-absorption process in CdSe parabolic quantum dots  

Science Conference Proceedings (OSTI)

The nonlinear susceptibilities have been calculated theoretically for CdSe disk-like parabolic quantum dots by using a two-energy-level model in the strong-confinement regime. The confined wave functions and eigenenergies of excitons in parabolic quantum ... Keywords: Electro-optical effects, Excitons, Parabolic quantum dot

Shufei Xie; Guiguang Xiong; Xiaobo Feng; Zhihong Chen

2007-06-01T23:59:59.000Z

163

Implications of Simultaneous Requirements for Low Noise Exchange Gates in Double Quantum Dots  

E-Print Network (OSTI)

Achieving low-error, exchange-interaction operations in quantum dots for quantum computing imposes simultaneous requirements on the exchange energy's dependence on applied voltages. A double quantum dot (DQD) qubit, approximated with a quadratic potential, is solved using a full configuration interaction method. This method is more accurate than Heitler-London and Hund-Mulliken approaches and captures new and significant qualitative behavior. We show that multiple regimes can be found in which the exchange energy's dependence on the bias voltage between the dots is compatible with current quantum error correction codes and state-of-the-art electronics. Identifying such regimes may prove valuable for the construction and operation of quantum gates that are robust to charge fluctuations, particularly in the case of dynamically corrected gates.

Nielsen, Erik; Muller, Richard P; Carroll, M S

2010-01-01T23:59:59.000Z

164

Implications of Simultaneous Requirements for Low Noise Exchange Gates in Double Quantum Dots  

E-Print Network (OSTI)

Achieving low-error, exchange-interaction operations in quantum dots for quantum computing imposes simultaneous requirements on the exchange energy's dependence on applied voltages. A double quantum dot (DQD) qubit, approximated with a quadratic potential, is solved using a full configuration interaction method. This method is more accurate than Heitler-London and Hund-Mulliken approaches and captures new and significant qualitative behavior. We show that multiple regimes can be found in which the exchange energy's dependence on the bias voltage between the dots is compatible with current quantum error correction codes and state-of-the-art electronics. Identifying such regimes may prove valuable for the construction and operation of quantum gates that are robust to charge fluctuations, particularly in the case of dynamically corrected gates.

Erik Nielsen; Ralph W. Young; Richard P. Muller; M. S. Carroll

2009-08-31T23:59:59.000Z

165

Tunnel-injection GaN quantum dot ultraviolet light-emitting diodes  

SciTech Connect

We demonstrate a GaN quantum dot ultraviolet light-emitting diode that uses tunnel injection of carriers through AlN barriers into the active region. The quantum dot heterostructure is grown by molecular beam epitaxy on AlN templates. The large lattice mismatch between GaN and AlN favors the formation of GaN quantum dots in the Stranski-Krastanov growth mode. Carrier injection by tunneling can mitigate losses incurred in hot-carrier injection in light emitting heterostructures. To achieve tunnel injection, relatively low composition AlGaN is used for n- and p-type layers to simultaneously take advantage of effective band alignment and efficient doping. The small height of the quantum dots results in short-wavelength emission and are simultaneously an effective tool to fight the reduction of oscillator strength from quantum-confined Stark effect due to polarization fields. The strong quantum confinement results in room-temperature electroluminescence peaks at 261 and 340 nm, well above the 365 nm bandgap of bulk GaN. The demonstration opens the doorway to exploit many varied features of quantum dot physics to realize high-efficiency short-wavelength light sources.

Verma, Jai; Kandaswamy, Prem Kumar; Protasenko, Vladimir; Verma, Amit; Grace Xing, Huili; Jena, Debdeep [Department of Electrical Engineering, University of Notre Dame, Indiana 46556 (United States)] [Department of Electrical Engineering, University of Notre Dame, Indiana 46556 (United States)

2013-01-28T23:59:59.000Z

166

Trapping of charge carriers into InAs/AlAs quantum dots at liquid-helium temperature  

Science Conference Proceedings (OSTI)

The problem of how the probability of trapping of charge carriers into quantum dots via the wetting layer influences the steady-state and time-dependent luminescence of the wetting layer and quantum dots excited via the matrix is analyzed in the context of some simple models. It is shown that the increase in the integrated steady-state luminescence intensity of quantum dots with increasing area fraction occupied by the quantum dots in the structure is indicative of the suppression of trapping of charge carriers from the wetting layer into the quantum dots. The same conclusion follows from the independent decays of the time-dependent luminescence signals from the wetting layer and quantum dots. The processes of trapping of charge carriers into the InAs quantum dots in the AlAs matrix at 5 K are studied experimentally by exploring the steady-state and time-dependent photoluminescence. A series of structures with different densities of quantum dots has been grown by molecular-beam epitaxy on a semi-insulating GaAs (001) substrate. It is found that the integrated photoluminescence intensity of quantum dots almost linearly increases with increasing area occupied with the quantum dots in the structure. It is also found that, after pulsed excitation, the photoluminescence intensity of the wetting layer decays more slowly than the photoluminescence intensity of the quantum dots. According to the analysis, these experimental observations suggest that trapping of excitons from the wetting layer into the InAs/AlAs quantum dots at 5 K is suppressed.

Abramkin, D. S., E-mail: demid@thermo.isp.nsc.ru; Zhuravlev, K. S.; Shamirzaev, T. S.; Nenashev, A. V.; Kalagin, A. K. [Russian Academy of Sciences, Institute of Semiconductor Physics, Siberian Branch (Russian Federation)

2011-02-15T23:59:59.000Z

167

NREL Researchers Demonstrate External Quantum Efficiency Surpassing 100% in a Quantum Dot Solar Cell (Fact Sheet)  

DOE Green Energy (OSTI)

A new device that produces and collects multiple electrons per photon could yield inexpensive, high-efficiency photovoltaics. A new device developed through research at the National Renewable Energy Laboratory (NREL) reduces conventional losses in photovoltaic (PV) solar cells, potentially increasing the power conversion efficiency-but not the cost-of the solar cells. Solar cells convert optical energy from the sun into usable electricity; however, almost 50% of the incident energy is lost as heat with present-day technologies. High-efficiency, multi-junction cells reduce this heat loss, but their cost is significantly higher. NREL's new device uses excess energy in solar photons to create extra charges rather than heat. This was achieved using 5-nanometer-diameter quantum dots of lead selenide (PbSe) tightly packed into a film. The researchers chemically treated the film, and then fabricated a device that yielded an external quantum efficiency (number of electrons produced per incident photon) exceeding 100%, a value beyond that of all current solar cells for any incident photon. Quantum dots are known to efficiently generate multiple excitons (a bound electron-hole pair) per absorbed high-energy photon, and this device definitively demonstrates the collection of multiple electrons per photon in a PV cell. The internal quantum efficiency corrects for photons that are not absorbed in the photoactive layer and shows that the PbSe film generates 30% to 40% more electrons in the high-energy spectral region than is possible with a conventional solar cell. While the unoptimized overall power conversion efficiency is still low (less than 5%), the results have important implications for PV because such high quantum efficiency can lead to more electrical current produced than possible using present technologies. Furthermore, this fabrication is also amenable to inexpensive, high-throughput roll-to-roll manufacturing.

Not Available

2011-12-01T23:59:59.000Z

168

Fast Electrical Control of a Quantum Dot Strongly Coupled to a Nano-resonator  

E-Print Network (OSTI)

The resonance frequency of an InAs quantum dot strongly coupled to a GaAs photonic crystal cavity was electrically controlled via quantum confined Stark effect. Stark shifts up to 0.3meV were achieved using a lateral Schottky electrode that created a local depletion region at the location of the quantum dot. We report switching of a probe laser coherently coupled to the cavity up to speeds as high as 150MHz, limited by the RC constant of the transmission line. The coupling rate and the magnitude of the Stark shift with electric field were investigated while coherently probing the system.

Andrei Faraon; Arka Majumdar; Hyochul Kim; Pierre Petroff; Jelena Vuckovic

2009-06-03T23:59:59.000Z

169

Inhibition of plasmonically enhanced interdot energy transfer in quantum dot solids via photo-oxidation  

Science Conference Proceedings (OSTI)

We studied the impact of photophysical and photochemical processes on the interdot Forster energy transfer in monodisperse CdSe/ZnS quantum dot solids. For this, we investigated emission spectra of CdSe/ZnS quantum dot solids in the vicinity of gold metallic nanoparticles coated with chromium oxide. The metallic nanoparticles were used to enhance the rate of the energy transfer between the quantum dots, while the chromium oxide coating led to significant increase of their photo-oxidation rates. Our results showed that irradiation of such solids with a laser beam can lead to unique spectral changes, including narrowing and blue shift. We investigate these effects in terms of inhibition of the plasmonically enhanced interdot energy transfer between quantum dots via the chromium-oxide accelerated photo-oxidation process. We demonstrate this considering energy-dependent rate of the interdot energy transfer process, plasmonic effects, and the way photo-oxidation enhances non-radiative decay rates of quantum dots with different sizes.

Sadeghi, S. M. [Department of Physics, University of Alabama in Huntsville, Huntsville, Alabama 35899 (United States); Nano and Micro Device Center, University of Alabama in Huntsville, Huntsville, Alabama 35899 (United States); Nejat, A.; West, R. G. [Department of Physics, University of Alabama in Huntsville, Huntsville, Alabama 35899 (United States)

2012-11-15T23:59:59.000Z

170

Photoluminescence properties of cadmium-selenide quantum dots embedded in a liquid-crystal polymer matrix  

SciTech Connect

The photoluminescence properties of cadmium-selenide (CdSe) quantum dots with an average size of {approx}3 nm, embedded in a liquid-crystal polymer matrix are studied. It was found that an increase in the quantum-dot concentration results in modification of the intrinsic (exciton) photoluminescence spectrum in the range 500-600 nm and a nonmonotonic change in its intensity. Time-resolved measurements show the biexponential decay of the photoluminescence intensity with various ratios of fast and slow components depending on the quantum-dot concentration. In this case, the characteristic lifetimes of exciton photoluminescence are 5-10 and 35-50 ns for the fast and slow components, respectively, which is much shorter than the times for colloidal CdSe quantum dots of the same size. The observed features of the photoluminescence spectra and kinetics are explained by the effects of light reabsorption, energy transfer from quantum dots to the liquid-crystal polymer matrix, and the effect of the electronic states at the CdSe/(liquid crystal) interface.

Tselikov, G. I., E-mail: gleb@vega.phys.msu.ru; Timoshenko, V. Yu. [Moscow State University, Faculty of Physics (Russian Federation); Plenge, J.; Ruehl, E. [Free University of Berlin, Institute of Chemistry and Biochemistry (Germany); Shatalova, A. M.; Shandryuk, G. A.; Merekalov, A. S.; Tal'roze, R. V. [Russian Academy of Sciences, Topchiev Institute of Petrochemical Synthesis (Russian Federation)

2013-05-15T23:59:59.000Z

171

Double quantum dot with tunable coupling in a Si MOS device with lateral geometry.  

Science Conference Proceedings (OSTI)

We report low-temperature transport measurements of a silicon metal-oxide-semiconductor (MOS) double quantum dot (DQD). In contrast to previously reported measurements of DQD's in Si MOS structures, our device has a lateral gate geometry very similar to that used by Petta et al. to demonstrate coherent manipulation of single electron spins. This gate design provides a high degree of tunability, allowing for independent control over individual dot occupation and tunnel barriers, as well as the ability to use nearby constrictions to sense dot charge occupation. Comparison of experimentally extracted capacitances between the dot and nearby gates with electrostatic modeling demonstrates the presence of disorder and the ability to partially compensate for this disorder by adjustment of gate voltages. We experimentally show gate-controlled tuning of the interdot coupling over a wide range of energies, an important step towards potential quantum computing applications.

Wendt, Joel Robert; Ten Eyck, Gregory A.; Childs, Kenton David; Tracy, Lisa A.; Pinilla, C. Borras (University of Oklahoma, Norman, OK); Eng, Kevin; Eriksson, Mark A. (University of Wisconsin-Madison, Madison, WI); Nordberg, Eric; Carroll, Malcolm S.; Stevens, J.; Young, Ralph Watson; Lilly, Michael Patrick; Stalford, Harold Lenn

2010-08-01T23:59:59.000Z

172

Determination of energy scales in few-electron double quantum dots  

SciTech Connect

The capacitive couplings between gate-defined quantum dots and their gates vary considerably as a function of applied gate voltages. The conversion between gate voltages and the relevant energy scales is usually performed in a regime of rather symmetric dot-lead tunnel couplings strong enough to allow direct transport measurements. Unfortunately, this standard procedure fails for weak and possibly asymmetric tunnel couplings, often the case in realistic devices. We have developed methods to determine the gate voltage to energy conversion accurately in the different regimes of dot-lead tunnel couplings and demonstrate strong variations of the conversion factors. Our concepts can easily be extended to triple quantum dots or even larger arrays.

Taubert, D.; Ludwig, S. [Center for NanoScience and Fakultaet fuer Physik, Ludwig-Maximilians-Universitaet Muenchen, Geschwister-Scholl-Platz 1, D-80539 Muenchen (Germany); Schuh, D. [Institut fuer Experimentelle Physik, Universitaet Regensburg, D-93040 Regensburg (Germany); Wegscheider, W. [Laboratory for Solid State Physics, ETH Zuerich, CH-8093 Zuerich (Switzerland)

2011-12-15T23:59:59.000Z

173

Entanglement and bistability in coupled quantum dots inside a driven cavity  

SciTech Connect

Generation and dissipation of entanglement between two coupled quantum dots (QDs) in a cavity driven by a coherent field is studied. We find that it is possible to generate and sustain a large amount of entanglement between the quantum dots in the steady state, even in the presence of strong decay in both the cavity and the dots. We investigate the effect of different parameters (decay rates, coupling strengths, and detunings) on entanglement. We find that the cavity field shows bistability and study the effect of relevant parameters on the existence of this bistable behavior. We also study the correlation between the cavity field and the entanglement between the dots. The experimental viability of the proposed scheme is discussed.

Mitra, Arnab; Vyas, Reeta [Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701 (United States)

2010-01-15T23:59:59.000Z

174

Graphene quantum dots for valley-based quantum computing: A feasibility study  

E-Print Network (OSTI)

At the center of quantum computing1 realization is the physical implementation of qubits - two-state quantum information units. The rise of graphene2 has opened a new door to the implementation. Because graphene electrons simulate two-dimensional relativistic particles with two degenerate and independent energy valleys,3 a novel degree of freedom (d.o.f.), namely, the valley state of an electron, emerges as a new information carrier.4 Here, we expand the Loss-DiVincenzo quantum dot (QD) approach in electron spin qubits,5,6 and investigate the feasibility of double QD (DQD) structures in gapful graphene as "valley qubits", with the logic 0 / 1 states represented by the "valley" singlet / triplet pair. This generalization is characterized by 1) valley relaxation time ~ O(ms), and 2) electric qubit manipulation on the time scale ~ ns, based on the 1st-order "relativistic effect" unique in graphene. A potential for valley-based quantum computing is present.

G. Y. Wu; N. -Y. Lue; L. Chang

2011-04-04T23:59:59.000Z

175

Tunable Coulomb blockade and giant Coulomb blockade magnetoresistance in a double quantum dot array  

Science Conference Proceedings (OSTI)

We propose a Hubbard model to illuminate the tunneling effect of electrons in a double quantum dot array connected in the parallel circuit configuration to electrodes. The change in the interdot coupling is shown to dramatically influence the Coulomb blockade properties, consistent with earlier experimental observations. For magnetic double dots, the interdot coupling can be tuned by the external magnetic field, leading to a giant Coulomb blockade magnetoresistance.

Zhang, Xiaoguang [ORNL; Xiang, T. [Chinese Academy of Sciences

2011-01-01T23:59:59.000Z

176

Negative differential conductance in InAs wire based double quantum dot induced by a charged AFM tip  

Science Conference Proceedings (OSTI)

We investigate the conductance of an InAs nanowire in the nonlinear regime in the case of low electron density where the wire is split into quantum dots connected in series. The negative differential conductance in the wire is initiated by means of a charged atomic force microscope tip adjusting the transparency of the tunneling barrier between two adjoining quantum dots. We confirm that the negative differential conductance arises due to the resonant tunneling between these two adjoining quantum dots. The influence of the transparency of the blocking barriers and the relative position of energy states in the adjoining dots on a decrease of the negative differential conductance is investigated in detail.

Zhukov, A. A., E-mail: azhukov@issp.ac.ru [Russian Academy of Science, Institute of Solid State Physics (Russian Federation); Volk, Ch.; Winden, A.; Hardtdegen, H.; Schaepers, Th. [Peter Gruenberg Institut (PGI-9) (Germany)

2012-12-15T23:59:59.000Z

177

Polarized Emission from Single GaN Quantum Dots Grown by Molecular Beam Epitaxy  

Science Conference Proceedings (OSTI)

Polarization resolved microphotoluminescence measurements of single MBE-grown GaN/Al(Ga)N quantum dots (QDs) have been performed. The exciton and biexciton peaks with full width at half maximum as narrow as dots, resulting in different built-in electric field. Moreover, a strongly linearly polarized emission is observed for the investigated dots with a degree of linear polarization of about 0.9, interpreted as the valence-band mixing induced by in-plane anisotropy due to strain and/or QD shape.

Amloy, S. [Department of Physics, Chemistry, and Biology (IFM), Linkoeping University, S-58183 Linkoeping (Sweden); Department of Physics, Faculty of Science, Thaksin University, 93110 Phattalung (Thailand); Yu, K. H.; Karlsson, K. F.; Holtz, P. O. [Department of Physics, Chemistry, and Biology (IFM), Linkoeping University, S-58183 Linkoeping (Sweden); Farivar, R.; Andersson, T. G. [Applied Semiconductor Physics, Department of Microtechnology and Nanoscience, Chalmers University of Technology, S-41296 Goeteborg (Sweden)

2011-12-23T23:59:59.000Z

178

Improvements of stacked self-assembled InAs/GaAs quantum dot structures for 1.3µm applications  

Science Conference Proceedings (OSTI)

We propose the growth of thick 'spacer' layers (d) for high-quality 10-stack InAs/GaAs quantum dots (QDs) emitting at 1.23@mm without the use of strain reduction layers (SRLs). All samples were grown using molecular beam epitaxy (MBE) and extensively ... Keywords: Defect, Molecular beam epitaxy, Stacked quantum dot

J. Ng; M. Missous

2006-12-01T23:59:59.000Z

179

Effects of external fields on the excitonic emission from single InAs/GaAs quantum dots  

Science Conference Proceedings (OSTI)

A low-temperature micro-photoluminescence (?-PL) investigation of InAs/GaAs quantum dots (QDs) exposed to a lateral external electric field is reported. It is demonstrated that the QDs PL signal could be increased several times by altering the ... Keywords: Exciton, Micro-luminescence, Quantum dot

P. O. Holtz; E. S. Moskalenko; M. Larsson; K. F. Karlsson; W. V. Schoenfeld; P. M. Petroff

2008-03-01T23:59:59.000Z

180

Quantum Dots Promise to Significantly Boost Photovoltaic Efficiencies, The Spectrum of Clean Energy Innovation (Fact Sheet)  

NLE Websites -- All DOE Office Websites (Extended Search)

Semiconductor quantum dots used in so-called "third-generation" solar cells have the potential Semiconductor quantum dots used in so-called "third-generation" solar cells have the potential to dramatically increase-in some cases even double-the efficiency of converting sunlight to electricity. The conversion process works via "multiple exciton generation (MEG)." In this process, when a single photon of light of sufficient energy is absorbed by the quantum dot, it produces more than one bound electron-hole pair, or exciton. NREL scientists were the first to predict this important unusual MEG effect in QDs, which contrasts with conventional photo- voltaic (PV) cells having much larger crystals and many more atoms and in which one photon produces only one electron-hole pair. The electronic process is also very fast, occurring within

Note: This page contains sample records for the topic "quantum dot tracers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
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181

Rashba coupling in three-electron-quantum dot under cylindrical symmetry: An exact solution  

Science Conference Proceedings (OSTI)

The application of quantum dots in advanced technology goes beyond doubt. Here, based on an analytical methodology, investigate a three-electron-quantum dot in the presence of Rashba spin-orbit interaction under cylindrical symmetry. Both eigenvalues and eigenfunctions of the system are reported and the problem is numerically discussed. - Graphical abstract: Display Omitted Highlights: > We theoretically investigate a three-electron-quantum dot in the presence of Rashba spin-orbit interaction by an exact analytical methodology. > By using the Jacobi transformations as well as the hyperspherical coordinates we calculate the wavefunction and the energy spectra. > Our obtained energy relation reveals that the Rashba interaction appears solely in the center of mass section.

Hassanabadi, H., E-mail: h.hasanabadi@shahroodut.ac.ir [Physics Department, Shahrood University of Technology, P.O. Box 3619995161-316 Shahrood (Iran, Islamic Republic of); Rahimov, H. [Computer Engineering Department, Shahrood University of Technology, Shahrood (Iran, Islamic Republic of); Zarrinkamar, S. [Department of Basic Sciences, Garmsar Branch, Islamic Azad University, Garmsar (Iran, Islamic Republic of)

2011-11-15T23:59:59.000Z

182

Mn solid solutions in self-assembled Ge/Si (001) quantum dot heterostructures  

SciTech Connect

Heteroepitaxial Ge{sub 0.98}Mn{sub 0.02} quantum dots (QDs) on Si (001) were grown by molecular beam epitaxy. The standard Ge wetting layer-hut-dome-superdome sequence was observed, with no indicators of second phase formation in the surface morphology. We show that Mn forms a dilute solid solution in the Ge quantum dot layer, and a significant fraction of the Mn partitions into a sparse array of buried, Mn-enriched silicide precipitates directly underneath a fraction of the Ge superdomes. The magnetic response from the ultra-thin film indicates the absence of robust room temperature ferromagnetism, perhaps due to anomalous intermixing of Si into the Ge quantum dots.

Kassim, J.; Nolph, C.; Reinke, P.; Floro, J. [Department of Materials Science and Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States); Jamet, M. [Institut Nanosciences et Cryogenie/SP2M, CEA-UJF, F-38054 Grenoble (France)

2012-12-10T23:59:59.000Z

183

Design of quantum dot lattices in amorphous matrices by ion beam irradiation  

Science Conference Proceedings (OSTI)

We report on the highly controllable self-assembly of semiconductor quantum dots and metallic nanoparticles in a solid amorphous matrix, induced by ion beam irradiation of an amorphous multilayer. We demonstrate experimentally and theoretically a possibility to tune the basic structural properties of the quantum dots in a wide range. Furthermore, the sizes, distances, and arrangement type of the quantum dots follow simple equations dependent on the irradiation and the multilayer properties. We present a Monte Carlo model for the simulation and prediction of the structural properties of the materials formed by this method. The presented results enable engineering and simple production of functional materials or simple devices interesting for applications in nanotechnology.

Buljan, M.; Bogdanovic-Radovic, I.; Karlusic, M.; Desnica, U. V.; Radic, N.; Jaksic, M.; Salamon, K.; Drazic, G.; Bernstorff, S.; Holy, V. [Rudjer Boskovic Institute, Bijenicka cesta 54, HR-10000 Zagreb (Croatia); Institute of Physics, Bijenicka cesta 46, HR-10000 Zagreb (Croatia); Jozef Stefan Institute, Jamova 39, SLO-1000 Ljubljana (Slovenia); Sincrotrone Trieste, I-34149 Basovizza (Italy); Charles University in Prague, CZ-12116 Prague (Czech Republic)

2011-10-15T23:59:59.000Z

184

Luminescence of CdSe/ZnS quantum dots infiltrated into an opal matrix  

SciTech Connect

The effect of the photonic band gap in the photonic crystal, the synthesized SiO{sub 2} opal with embedded CdSe/ZnS quantum dots, on its luminescence in the visible spectral region is studied. It is shown that the position of the photonic band gap in the luminescence and reflectance spectra for the infiltrated opal depends on the diameter of the constituent nanospheres and on the angle of recording the signal. The optimal conditions for embedding the CdSe/ZnS quantum dots from the solution into the opal matrix are determined. It is found that, for the opal-CdSe/ZnS nanocomposites, the emission intensity decreases and the luminescence decay time increases in the spatial directions, in which the spectral positions of the photonic band gap and the luminescence peak of the quantum dots coincide.

Gruzintsev, A. N. [Russian Academy of Sciences, Institute of Microelectronics Technology and Ultra-High-Purity Materials (Russian Federation)], E-mail: gran@ipmt-hpm.ac.ru; Emelchenko, G. A.; Masalov, V. M. [Russian Academy of Sciences, Institute of Solid State Physics (Russian Federation); Yakimov, E. E. [Russian Academy of Sciences, Institute of Microelectronics Technology and Ultra-High-Purity Materials (Russian Federation); Barthou, C.; Maitre, A. [Institut des NanoSciences (France)

2009-02-15T23:59:59.000Z

185

Quantitative Excited State Spectroscopy of a Single InGaAs Quantum Dot Molecule through Multi-million Atom Electronic Structure Calculations  

E-Print Network (OSTI)

Atomistic electronic structure calculations are performed to study the coherent inter-dot couplings of the electronic states in a single InGaAs quantum dot molecule. The experimentally observed excitonic spectrum [12] is quantitatively reproduced, and the correct energy states are identified based on a previously validated atomistic tight binding model. The extended devices are represented explicitly in space with 15 million atom structures. An excited state spectroscopy technique is presented in which the externally applied electric field is swept to probe the ladder of the electronic energy levels (electron or hole) of one quantum dot through anti-crossings with the energy levels of the other quantum dot in a two quantum dot molecule. Such technique can be applied to estimate the spatial electron-hole spacing inside the quantum dot molecule as well as to reverse engineer the quantum dot geometry parameters such as the quantum dot separation. Crystal deformation induced piezoelectric effects have been discus...

Usman, Muhammad; Ryu, Hoon; Ahmed, Shaikh; Boykin, Timothy; Klimeck, Gerhard

2011-01-01T23:59:59.000Z

186

Dispersive Coupling Between the Superconducting Transmission Line Resonator and the Double Quantum Dots  

E-Print Network (OSTI)

Realization of controllable interaction between distant qubits is one of the major problems in scalable solid state quantum computing. We study a superconducting transmission line resonator (TLR) as a tunable dispersive coupler for the double-dot molecules. A general interaction Hamiltonian of $n$ two-electron spin-based qubits and the TLR is presented, where the double-dot qubits are biased at the large detuning region and the TLR is always empty and virtually excited. Our analysis o the main decoherence sources indicates that various major quantum operations can be reliably implemented with current technology.

Guo-Ping Guo; Hui Zhang; Yong Hu; Tao Tu; Guang-Can Guo

2008-02-10T23:59:59.000Z

187

Temperature-dependent energy band gap variation in self-organized InAs quantum dots  

SciTech Connect

We investigated the temperature-dependent variation of the photoluminescence emission energy of self-organized InAs/GaAs quantum dots (QDs) grown by conventional Stranski-Krastanov (SK) molecular beam epitaxy and migration-enhanced molecular beam epitaxy (MEMBE) and that of MEMBE InAs QDs in a symmetric and an asymmetric In{sub 0.2}Ga{sub 0.8}As/GaAs well. The temperature-dependent energy variation of each QD is analyzed in low and high temperature regions, including a sigmoidal behavior of conventional SK quantum dots with the well-known Varshni and semi-empirical Fan models.

Yeo, Inah [CEA/CNRS/UJF Joint Team ''Nanophysics and Semiconductors,'' Institut Neel-CNRS, BP 166, 25 rue des Martyrs, 38042 Grenoble Cedex 9 (France); Dong Song, Jin; Lee, Jungil [Nanophotonics Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of)

2011-10-10T23:59:59.000Z

188

Electronic excitations and transport in aperiodic sequences of quantum dots in external electric and magnetic fields  

Science Conference Proceedings (OSTI)

The energy spectra and transport of electronic excitations in one-dimensional aperiodic sequences of quantum dots of Thue-Morse and double-periodic type are studied. The influence of external magnetic and electric fields on the energy spectra and transport is considered. For aperiodic sequences of quantum dots, in contrast to aperiodic sequences of atoms, the influence of relatively small magnetic and electric fields is essential, but localization occurs at finite values of the perturbations. The transmission coefficient is determined using the quasiclassical approximation with the Coulomb blockade taken into account. The resonance tunneling is studied.

Korotaev, P. Yu., E-mail: pvl.korotaev@gmail.com; Kaputkina, N. E. [National University of Science and Technology 'MISIS' (Russian Federation); Lozovik, Yu. E. [Russian Academy of Sciences, Institute of Spectroscopy (Russian Federation); Vekilov, Yu. Kh. [National University of Science and Technology 'MISIS' (Russian Federation)

2011-10-15T23:59:59.000Z

189

Bright CdSe quantum dot inserted in single ZnSe nanowires  

Science Conference Proceedings (OSTI)

We report the evidence of CdSe quantum dot (QD) insertion in single defect-free ZnSe nanowire. These nanowires have been grown by molecular beam epitaxy in vapour-liquid-solid growth mode catalysed with gold particles. We developed a two-step process ... Keywords: µPL, Antibunching, CdSe, Correlation measurement, Micro photoluminescence, Polarisation, Single NW, Single QD, Single nanowire, Single nanowire heterostructures, Single quantum dot, TRPL, Time-resolved photoluminescence, Two-step process, ZnSe

A. Tribu; G. Sallen; T. Aichele; C. Bougerol; R. André; J. P. Poizat; S. Tatarenko; K. Kheng

2009-02-01T23:59:59.000Z

190

Simulation of a broadband nano-biosensor based on an onion-like quantum dot-quantum well structure  

Science Conference Proceedings (OSTI)

The fluorescence resonance energy transfer is studied between modified quantum-dots and quantum-wells used as a donor and an acceptor. Because of the unique properties of quantum dots, including diverse surface modification flexibility, bio-compatibility, high quantum yields and wide absorption, their use as nano-biosensors and bio-markers used in diagnosis of cancer is suggested. The fluorescence resonance energy transfer is simulated in a quantum dot-quantum well system, where the energy can flow from donor to acceptor. If the energy transfer can be either turned on or off by a specific interaction, such as interaction with any dyes, a molecular binding event or a cleavage reaction, a sensor can be designed (under assumption that the healthy cells have a known effect or unyielding effect on output parameters while cancerous cells, due to their pandemic optical properties, can impact the fluorescence resonance energy transfer parameters). The developed nano-biosensor can operate in a wide range of wavelengths (310 - 760 nm). (laser applications in biology and medicine)

Absalan, H; SalmanOgli, A; Rostami, R

2013-07-31T23:59:59.000Z

191

X-ray luminescence of CdTe quantum dots in LaF{sub 3}:Ce/CdTe nanocomposites  

Science Conference Proceedings (OSTI)

CdTe quantum dots have intense photoluminescence but exhibit almost no x-ray luminescence. However, intense x-ray luminescence from CdTe quantum dots is observed in LaF{sub 3}:Ce/CdTe nanocomposites. This enhancement in the x-ray luminescence of CdTe quantum dots is attributed to the energy transfer from LaF{sub 3}:Ce to CdTe quantum dots in the nanocomposites. The combination of LaF{sub 3}:Ce nanoparticles and CdTe quantum dots makes LaF{sub 3}:Ce/CdTe nanocomposites promising scintillators for radiation detection.

Hossu, Marius; Liu Zhongxin; Yao Mingzhen; Ma Lun; Chen Wei

2012-01-02T23:59:59.000Z

192

Ambient Air Sampling During Quantum-dot Spray Deposition  

Science Conference Proceedings (OSTI)

Ambient air sampling for nano-size particle emissions was performed during spot spray coating operations with a Sono-Tek Exactacoat Benchtop system (ECB). The ECB consisted of the application equipment contained within an exhaust enclosure. The enclosure contained numerous small access openings, including an exhaust hook-up. Door access comprised most of the width and height of the front. The door itself was of the swing-out type. Two types of nanomaterials, Cadmium selenide (Cd-Se) quantum-dots (QDs) and Gold (Au) QDs, nominally 3.3 and 5 nm in diameter respectively, were applied during the evaluation. Median spray drop size was in the 20 to 60 micrometer size range.1 Surface coating tests were of short duration, on the order of one-half second per spray and ten spray applications between door openings. The enclosure was ventilated by connection to a high efficiency particulate aerosol (HEPA) filtered house exhaust system. The exhaust rate was nominally 80 ft3 per minute producing about 5 air changes per minute. Real time air monitoring with a scanning mobility particle size analyzer (SMPS ) with a size detection limit of 7 nm indicated a significant increase in the ambient air concentration upon early door opening. A handheld condensation particle counter (CPC) with a lower size limit of 10 nm did not record changes in the ambient background. This increase in the ambient was not observed when door opening was delayed for 2 minutes (~10 air changes). The ventilated enclosure controlled emissions except for cases of rapid door opening before the overspray could be removed by the exhaust. A time delay sufficient to provide 10 enclosure air changes (a concentration reduction of more than 99.99 %) before door opening prevented the release of aerosol particles in any size.2 Scanning-transmission electron microscopy (STEM) and atomic force microscopy (AFM) demonstrated the presence of agglomerates in the surfaces of the spray applied deposition. A filtered air sample of the enclosure overspray examined by AFM also demonstrated the presence of agglomerates for the Au QDs. The AFM system was not able to resolve individual QDs as was the STEM. Chemical fingerprinting of the QDs with STEM/EDS (energy dispersive spectroscopy) was performed for the Cd-Se surface deposition, but not the aerosol. Both STEM and AFM background characterization by morphology and chemical fingerprinting were performed throughout the laboratory for a period of about one year. Outdoor sources were primarily biological, combustion fume, salt and other crustal particles. Indoor sources were primarily paper/clothing fibers, spray-on insulation fragments, fiber glass, and human skin cells.

Jankovic, John Timothy [ORNL; Hollenbeck, Scott M [ORNL

2010-01-01T23:59:59.000Z

193

Controlling the emission from semiconductor quantum dots using ultra-small tunable optical microcavities  

E-Print Network (OSTI)

We report the control of spontaneous emission from CdSe/ZnS core-shell quantum dots coupled to novel open-access optical microcavities. The cavities are fabricated by focused ion beam milling, and provide mode volumes less than a cubic micrometre. The quantum dot emission spectrum, spatial modes, and lifetime are all modified substantially by the presence of the cavity, and can be tuned by actively varying the cavity length. An increase in emission rate of 75% is achieved at room temperature, attributed to the Purcell effect in the 'bad emitter' regime. We demonstrate a high degree of control over the emission from the dots, including near single-mode operation and the ability to detect strong emission from individual nanocrystals.

Ziyun Di; Helene V. Jones; Philip R. Dolan; Simon M. Fairclough; Matthew B Wincott; Johnny Fill; Gareth M. Hughes; Jason M. Smith

2012-06-26T23:59:59.000Z

194

Voltage-tunable singlet-triplet transition in lateral quantum dots  

E-Print Network (OSTI)

Results of calculations and high source-drain transport measurements are presented which demonstrate voltage-tunable entanglement of electron pairs in lateral quantum dots. At a fixed magnetic field, the application of a judiciously-chosen gate voltage alters the ground-state of an electron pair from an entagled spin singlet to a spin triplet.

Jordan Kyriakidis; M. Pioro-Ladriere; M. Ciorga; A. S. Sachrajda; P. Hawrylak

2001-11-28T23:59:59.000Z

195

Evidence for formation of multi-quantum dots in hydrogenated graphene  

E-Print Network (OSTI)

of the multi-quantum dots, which is not observed in pristine graphene to date, was attributed to the impurities and defects unintentionally decorated on a single-layer graphene flake which was not treated with the thermal annealing process. Graphene multi...

Chuang, Chiashain; Puddy, Reuben K; Connolly, Malcolm R; Lo, Shun-Tsung; Lin, Huang-De; Chen, Tse-Ming; Smith, Charles G; Liang, Chi-Te

2012-08-16T23:59:59.000Z

196

A flow cytometry-based dopamine transporter binding assay using antagonist-conjugated quantum dots  

SciTech Connect

Here we present the development and validation of a flow cytometry-based dopamine transporter (DAT) binding assay that uses antagonist-conjugated quantum dots (QDs).We anticipate that our QD-based assay is of immediate value to the high throughput screening of novel DAT modulators.

Kovtun, Oleg [Department of Chemistry, Vanderbilt University, 7300 Stevenson Ctr Ln, Nashville, TN 37235, USA.; Ross, Emily [Vanderbilt University; Tomlinson, Ian [Oak Ridge National Laboratory (ORNL); Rosenthal, Sandra [ORNL

2012-01-01T23:59:59.000Z

197

A first-principle study of B- and P-doped silicon quantum dots  

Science Conference Proceedings (OSTI)

Doping of silicon quantum dots (Si QDs) is important for realizing the potential applications of Si QDs in the fields of Si QDsbased all-Si tandem solar cells, thin-film transistors, and optoelectronic devices. Based on the first-principle calculations, ...

Jieqiong Zeng; Hong Yu

2012-01-01T23:59:59.000Z

198

Synthesis and characterization of blue emitting ZnSe quantum dots  

Science Conference Proceedings (OSTI)

In this work we show a new experimental methodology to obtain ZnSe nanocrystals in aqueous solution aiming their application as biophotonic probes. The nanocrystals were obtained using a simple procedure based on the arrested precipitation of ZnSe in ... Keywords: Blue emission, Colloidal synthesis, Water soluble quantum dots, ZnSe

J. J. Andrade; A. G. Brasil, Jr.; P. M. A. Farias; A. Fontes; B. S. Santos

2009-03-01T23:59:59.000Z

199

Exciton spectroscopy on single CdSe/ZnSe quantum dot photodiodes  

Science Conference Proceedings (OSTI)

We have investigated the properties of neutral and charged excitons in single CdSe/ZnSe QD photodiodes by @m-photoluminescence spectroscopy. By applying a bias voltage, we have been able to control the number of electrons in a single QD by shifting the ... Keywords: CdSe quantum dots, Photodiode, Stark effect

S. Michaelis de Vasconcellos; A. Pawlis; C. Arens; M. Panfilova; A. Zrenner; D. Schikora; K. Lischka

2009-02-01T23:59:59.000Z

200

Comparison of quantum-mechanical and semiclassical approaches for an analysis of spin dynamics in quantum dots  

Science Conference Proceedings (OSTI)

Two approaches to the description of spin dynamics of electron-nuclear system in quantum dots are compared: the quantum-mechanical one is based on direct diagonalization of the model Hamiltonian and semiclassical one is based on coupled equations for precession of mean electron spin and mean spin of nuclear spin fluctuations. The comparison was done for a model problem describing periodic excitation of electron-nuclear system by optical excitation. The computation results show that scattering of parameters related to fluctuation of the nuclear spin system leads to appearance of an ordered state in the system caused by periodic excitation and to the effect of electron-spin mode locking in an external magnetic field. It is concluded that both models can qualitatively describe the mode-locking effect, however give significantly different quantitative results. This may indicate the limited applicability of the precession model for describing the spin dynamics in quantum dots in the presence of optical pumping.

Petrov, M. Yu., E-mail: m.petrov@spbu.ru; Yakovlev, S. V. [Saint Petersburg State University (Russian Federation)

2012-08-15T23:59:59.000Z

Note: This page contains sample records for the topic "quantum dot tracers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

Cooling an electron gas using quantum dot based electronic refrigeration  

E-Print Network (OSTI)

of the QDR experiment have been published in: • J. R. Prance, C. G. Smith, J. P. Griffiths, S. J. Chorley, D. Anderson, G. A. C. Jones, I. Farrer, and D. A. Ritchie, Electronic refrigeration of a two- dimensional electron gas, Phys. Rev. Lett. 102(14), 146602... for the electrochemical potential of the dot: we define µN :i,j = Ui(N)?Uj(N ? 1), where Ui(N) is the energy of the dot holding N electrons with the last electron in the ith excited state. For example, the previous definition of µN is equivalent to µN :0,0. (The...

Prance, Jonathan Robert

2009-10-13T23:59:59.000Z

202

Voltage tunability of single spin-states in a quantum dot  

E-Print Network (OSTI)

Single spins in the solid-state offer a unique opportunity to store and manipulate quantum information, and to perform quantum-enhanced sensing of local fields and charges. Optical control of these systems using techniques developed in atomic physics has yet to exploit all the advantages of the solid-state. We demonstrate voltage tunability of the spin energy levels in a single quantum dot by modifying how spins sense magnetic field. We find the in-plane g-factor varies discontinuously for electrons, as more holes are loaded onto the dot. In contrast, the in-plane hole g-factor varies continuously. The device can change the sign of the in-plane g-factor of a single hole, at which point an avoided crossing is observed in the two spin eigenstates. This is exactly what is required for universal control of a single spin with a single electrical gate.

Anthony J. Bennett; Matthew A. Pooley; Yameng Cao; Niklas Sköld; Ian Farrer; David A. Ritchie; Andrew J. Shields

2013-02-27T23:59:59.000Z

203

Resonant Regimes in the Fock-Space Coherence of Multilevel Quantum Dots  

E-Print Network (OSTI)

The coherence between quantum states with different particle numbers --- the Fock-space coherence --- qualitatively differs from the more common Hilbert-space coherence between states with equal particle numbers. For a quantum dot with multiple channels available for transport, we find the conditions for decoupling the dynamics of the Fock-space coherence from both the Hilbert-space coherence as well as the population dynamics. We further find specific energy and coupling regimes where a long-lived resonance in the Fock-space coherence of the system is realized, even where no resonances are found either in the populations or Hilbert-space coherence. Numerical calculations show this resonance remains robust in the presence of both boson-mediated relaxation and transport through the quantum dot.

Eduardo Vaz; Jordan Kyriakidis

2011-05-26T23:59:59.000Z

204

Inhomogeneous dynamic nuclear polarization and suppression of electron-polarization decay in a quantum dot  

E-Print Network (OSTI)

We investigate the dynamic nuclear polarization process by frequently injecting polarized electron spins into a quantum dot. Due to the suppression of the direct dipolar and indirect electron-mediated nuclear spin interactions, by the frequently injected electron spins, the analytical predictions under the independent spin approximation agree well with quantum numerical simulations. Our results show that the acquired nuclear polarization is highly inhomogeneous, proportional to the square of the local electron-nuclear hyperfine interaction constant, if the injection frequency is high. Utilizing the inhomogeneously polarized nuclear spins as an initial state, we further show that the electron-polarization decay time can be extended 100 times even at a relatively low nuclear polarization (<20%), without much suppression of the fluctuation of the Overhauser field. Our results lay the foundation for future investigations of the effect of DNP in more complex spin systems, such as double quantum dots and nitrogen vacancy centers in diamonds.

Na Wu; Wenkui Ding; Anqi Shi; Wenxian Zhang

2013-03-04T23:59:59.000Z

205

Entanglement transfer from electron spins to photons in spin light-emitting diodes containing quantum dots  

E-Print Network (OSTI)

We show that electron recombination using positively charged excitons in single quantum dots provides an efficient method to transfer entanglement from electron spins onto photon polarizations. We propose a scheme for the production of entangled four-photon states of GHZ type. From the GHZ state, two fully entangled photons can be obtained by a measurement of two photons in the linear polarization basis, even for quantum dots with observable fine structure splitting for neutral excitons and significant exciton spin decoherence. Because of the interplay of quantum mechanical selection rules and interference, maximally entangled electron pairs are converted into maximally entangled photon pairs with unity fidelity for a continuous set of observation directions. We describe the dynamics of the conversion process using a master-equation approach and show that the implementation of our scheme is feasible with current experimental techniques.

Veronica Cerletti; Oliver Gywat; Daniel Loss

2004-11-09T23:59:59.000Z

206

Theoretical study of a localized quantum spin reversal by the sequential injection of spins in a spin quantum dot  

E-Print Network (OSTI)

This is a theoretical study of the reversal of a localized quantum spin induced by sequential injection of spins for a spin quantum dot that has a quantum spin. The system consists of ``electrode/quantum well(QW)/dot/QW/electrode" junctions, in which the left QW has an energy level of conduction electrons with only up-spin. We consider a situation in which up-spin electrons are sequentially injected from the left electrode into the dot through the QW and an exchange interaction acts between the electrons and the localized spin. To describe the sequentially injected electrons, we propose a simple method based on approximate solutions from the time-dependent Schr$\\ddot{\\rm o}$dinger equation. Using this method, it is shown that the spin reversal occurs when the right QW has energy levels of conduction electrons with only down-spin. In particular, the expression of the reversal time of a localized spin is derived and the upper and lower limits of the time are clearly expressed. This expression is expected to be useful for a rough estimation of the minimum relaxation time of the localized spin to achieve the reversal. We also obtain analytic expressions for the expectation value of the localized spin and the electrical current as a function of time. In addition, we found that a system with the non-magnetic right QW exhibits spin reversal or non-reversal depending on the exchange interaction.

Satoshi Kokado; Kazumasa Ueda; Kikuo Harigaya; Akimasa Sakuma

2007-08-10T23:59:59.000Z

207

Silanization of Low-Temperature-Plasma Synthesized Silicon Quantum Dots for Production of a Tunable, Stable, Colloidal Solution  

SciTech Connect

We present a method for grafting silanes onto low-temperature-plasma synthesized silicon quantum dots. The resulting solution of dots is characterized with Fourier transform infrared spectroscopy and transmission electron microscopy, and determined to be a colloidal suspension. The silane is attached at a single point on the quantum dot surface to avoid cross-linking and multilayer formation, and photoluminescence spectroscopy shows the colloidal suspension of dots is stable for over two months in air. The hydroxyl-terminated surfaces required for silanization are created by wet chemical etch, which can be used to tune the luminescence of the silicon dots in the green- to red-wavelength range. We find, however, that the wet etch cannot move the emission into the blue-wavelength range and discuss this observation in terms of the nature of etching process and origin of the emission. In addition, we discuss the photoluminescence quantum yield in the context of other passivation and synthetic techniques.

Anderson, I. E.; Shircliff, R. A.; Macauley, C.; Smith, D. K.; Lee, B. G.; Agrawal, S.; Stradins, P.; Collins, R. T.

2012-02-16T23:59:59.000Z

208

Voltage controlled nuclear polarization switching in a single InGaAs quantum dot  

E-Print Network (OSTI)

Sharp threshold-like transitions between two stable nuclear spin polarizations are observed in optically pumped individual InGaAs self-assembled quantum dots embedded in a Schottky diode when the bias applied to the diode is tuned. The abrupt transitions lead to the switching of the Overhauser field in the dot by up to 3 Tesla. The bias-dependent photoluminescence measurements reveal the importance of the electron-tunneling-assisted nuclear spin pumping. We also find evidence for the resonant LO-phonon-mediated electron co-tunneling, the effect controlled by the applied bias and leading to the reduction of the nuclear spin pumping rate.

M. N. Makhonin; J. Skiba-Szymanska; M. S. Skolnick; H. -Y. Liu; M. Hopkinson; A. I. Tartakovskii

2009-01-15T23:59:59.000Z

209

Generation of quantum-dot cluster states with superconducting transmission line resonator  

E-Print Network (OSTI)

We propose an efficient method to generate cluster states in spatially separated double quantum dots with a superconducting transmission line resonator (TLR). When the detuning between the double-dot qubits transition frequency and the frequency of the full wave mode in the TLR satisfies some conditions, an Ising-like operator between arbitrary two separated qubits can be achieved. Even including the main noise sources, it's shown that the high fidelity cluster states could be generated in this solid system in just one step.

Zhi-Rong Lin; Guo-Ping Guo; Tao Tu; Fei-Yun Zhu; Guang-Can Guo

2008-04-20T23:59:59.000Z

210

Generation of quantum-dot cluster states with superconducting transmission line resonator  

E-Print Network (OSTI)

We propose an efficient method to generate cluster states in spatially separated double quantum dots with a superconducting transmission line resonator (TLR). When the detuning between the double-dot qubits transition frequency and the frequency of the full wave mode in the TLR satisfies some conditions, an Ising-like operator between arbitrary two separated qubits can be achieved. Even including the main noise sources, it's shown that the high-fidelity cluster states could be generated in this solid system in just one step.

Lin, Zhi-Rong; Tu, Tao; Guo, Guang-Can; Guo, Guo-Ping

2008-01-01T23:59:59.000Z

211

Layer-by-layer surface manipulation and biointegration of quantum dots : assembly of nanostructured DNA delivery vehicles  

E-Print Network (OSTI)

Objectives: The aims of this investigation are to (i) prepare hybrid quantum dot (QD)-polymer compleses, (ii) maniplulate structural and chemical properties of the hybrids and characterize their effects on biocompatibility, ...

Jaffar, Saeeda Mahdi

2005-01-01T23:59:59.000Z

212

Exciton photoluminescence and energy in a percolation cluster of ZnSe quantum dots as a fractal object  

SciTech Connect

The results of studies of samples containing ZnSe quantum dots with a density corresponding to or considerably higher than the exciton percolation threshold, at which quantum dots form conglomerates, are reported. Excitonic emission from a percolation cluster of bound quantum dots as a fractal object is observed for the first time. Analysis of the structure of the photoluminescence spectra shows that the spectra are determined by the contribution of exciton states that belong to different structural elements of the percolation cluster, specifically, to the skeleton (backbone), dangling (dead) ends, and internal hollow spaces. A qualitative model is proposed to interpret the dependence of the exciton energy in these structural elements on the concentration of quantum dots in the material.

Bondar, N. V., E-mail: jbond@iop.kiev.ua; Brodyn, M. S. [National Academy of Sciences of Ukraine, Institute of Physics (Ukraine)

2012-05-15T23:59:59.000Z

213

Enhanced photorefractive performance in CdSe quantum-dot-dispersed poly(styrene-co-acrylonitrile) polymers  

Science Conference Proceedings (OSTI)

This paper reports on the enhanced photorefractive behavior of a CdSe quantum-dot-dispersed less expensive polymer of poly(styrene-co-acrylonitrile). The capability of CdSe quantum dots used as photosensitizers and the associated photorefractive performance are characterized through a photocurrent experiment and a two-beam coupling experiment, respectively. An enhanced two-beam coupling gain coefficient of 12.2 cm{sup -1} at 46 V/mum was observed owning to the reduced potential barrier. The photorefractive performance per CdSe quantum dot is three orders of magnitude higher than that in the sample sensitized by trinitrofluorenone in poly(styrene-co-acrylonitrile), and almost ten times higher than that in the CdSe quantum-dot-sensitized poly(N-vinylcarbazole) polymers.

Li Xiangping; Embden, Joel van; Chon, James W. M.; Gu Min [Centre for Micro-Photonics, Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, Hawthorn, Victoria 3122 (Australia); Evans, Richard A. [CSIRO Molecular and Health Technologies, Bag 10, Clayton South, Victoria 3169 (Australia)

2010-06-21T23:59:59.000Z

214

Microwave-assisted low temperature synthesis of wurtzite ZnS quantum dots  

SciTech Connect

In this work we report, for the first time, on microwave assisted synthesis of wurtzite ZnS quantum dots (QDs) in controlled reaction at temperature as low as 150 Degree-Sign C. The synthesis can be done in different microwave absorbing solvents with multisource or single source precursors. The QDs are less than 3 nm in size as characterized by transmission electron microscopy (TEM) using selected area electron diffraction (SAED) patterns to confirm the wurtzite phase of ZnS QDs. The optical properties were investigated by UV-Vis absorption which shows blue shift in absorption compared to bulk wurtzite ZnS due to quantum confinement effects. The photoluminescence (PL) spectra of QDs reveal point defects related emission of ZnS QDs. - Graphical abstract: Microwave assisted synthesis of wurtzite ZnS quantum dots (QDs) have been achieved in controlled reaction at temperature as low as 150 Degree-Sign C. The synthesis was performed in different microwave absorbing solvents with multisource or single source precursors for very short reaction periods due to effective heating with microwaves. Highlights: Black-Right-Pointing-Pointer Wurtzite a high temperature phase of ZnS was synthesized at low temperature. Black-Right-Pointing-Pointer Low temperature synthesis was possible because of the use of microwave absorbing solvents. Black-Right-Pointing-Pointer Capping agent was used to control the size of Quantum Dots. Black-Right-Pointing-Pointer Two different systems were developed using single molecular precursor and multisource precursors.

Shahid, Robina, E-mail: rkhan@kth.se [Division of Functional Materials, Royal Institute of Technology (KTH), 16440, Kista, Stockholm (Sweden); Toprak, Muhammet S., E-mail: toprak@kth.se [Division of Functional Materials, Royal Institute of Technology (KTH), 16440, Kista, Stockholm (Sweden); Muhammed, Mamoun [Division of Functional Materials, Royal Institute of Technology (KTH), 16440, Kista, Stockholm (Sweden)

2012-03-15T23:59:59.000Z

215

Carrier energy spectrum and lifetime in quantum dots in electric field  

Science Conference Proceedings (OSTI)

The S-matrix formalism is used to perform analytical calculations of the spectrum of quasi-stationary states of charge carriers in a core-shell quantum dot. Analytical expressions are obtained for the second-order perturbative corrections to the position and half-width of a quasi-stationary energy level, and level shifts are calculated numerically for a core-shell quantum dot in the presence of an electrostatic field. The corrections to level half-width due to Stark effect are analyzed as functions of level energy and barrier thickness. It is shown that there exists a level position E{sub cr} such that the correction {delta}{gamma} to the level half-width changes sign. An analytical expression for the quadratic Stark shift in a dc-biased quantum well is found in semiclassical approximation. It is shown that the corresponding correction {delta}{gamma} to half-width also changes sign as energy passes through E{sub cr}. As an example, the Stark shift is calculated for a core-shell quantum dot in the electrostatic field of an adjacent protein molecule.

Zegrya, G. G., E-mail: zegrya@theory.ioffe.ru; Samosvat, D. M. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation)], E-mail: samosvat@yandex.ru

2009-06-15T23:59:59.000Z

216

Creating a Precise Atomic-Scale Map of Quantum Dots | Advanced Photon  

NLE Websites -- All DOE Office Websites (Extended Search)

Getting to the Roots of Lethal Hairs Getting to the Roots of Lethal Hairs Stressing Out the Twins in Magnesium Size-Related Behavior of Anatase Nanocrystals under Extreme Pressure Boron-Based Compounds Trick a Biomedical Protein A Targeted Cancer Treatment using Nanomaterials Science Highlights Archives: 2013 | 2012 | 2011 | 2010 2009 | 2008 | 2007 | 2006 2005 | 2004 | 2003 | 2002 2001 | 2000 | 1998 | Subscribe to APS Science Highlights rss feed Creating a Precise Atomic-Scale Map of Quantum Dots OCTOBER 9, 2009 Bookmark and Share An atomic-scale map of the interface between an atomic dot and its substrate. Each peak represents a single atom. The map, made with high-intensity x-rays at the APS, is a slice through a vertical cross-section of the dot. (Image courtesy of Roy Clarke, University of

217

Spectral Barcoding of Quantum Dots: Deciphering Structural Motifs from the Excitonic Spectra  

Science Conference Proceedings (OSTI)

Self-assembled semiconductor quantum dots (QDs) show in high-resolution single-dot spectra a multitude of sharp lines, resembling a barcode, due to various neutral and charged exciton complexes. Here we propose the 'spectral barcoding' method that deciphers structural motifs of dots by using such barcode as input to an artificial-intelligence learning system. Thus, we invert the common practice of deducing spectra from structure by deducing structure from spectra. This approach (i) lays the foundation for building a much needed structure-spectra understanding for large nanostructures and (ii) can guide future design of desired optical features of QDs by controlling during growth only those structural motifs that decide given optical features.

Mlinar, V.; Zunger, A.

2009-01-01T23:59:59.000Z

218

Microchemical systems for the synthesis of nanostructures : quantum dots  

E-Print Network (OSTI)

We have developed a continuous multi-stage high-temperature and high-pressure microfluidic system. High-pressure conditions enabled the use low molecular weight solvents that have previously not been available for quantum ...

Baek, Jinyoung

2012-01-01T23:59:59.000Z

219

Thermal Imaging of Single Living Cells Using Semiconductor Quantum Dots  

E-Print Network (OSTI)

properties of colloidal CdSe/ZnS core/shell quantum dotsstrongly luminescing ZnS-Capped CdSe nanocrystals," JournalPhotochemical instability of CdSe nanocrystals coated by

Yang, Jui-Ming

2009-01-01T23:59:59.000Z

220

Synthesis of Non-blinking Semiconductor Quantum Dots Emitting in the Near-Infrared  

Science Conference Proceedings (OSTI)

Our previous work demonstrates that Quasi-Type II CdSe/CdS core-shell quantum dots with thick shells (3-5 nm) exhibit unique photophysical characteristics, including improved chemical robustness over typical thin-shelled core/shell systems and the elimination of blinking through suppression of nonradiative Auger recombination. Here we describe a new thick-shelled heterostructure, InP/CdS, which exhibits a Type II bandgap alignment producing near-infrared (NIR) emission. Samples with a range of shell thicknesses were synthesized, enabling shell-thickness-dependent study of the absorbance and emission spectra, fluorescence lifetimes, and quantum yields. InP/CdS/ZnS core/shell/shell structures were also synthesized to reduce cadmium exposure for applications in the biological environment. Single particle spectroscopy indicates reduced blinking and improved photostability with increasing shell thickness, resulting in thick-shelled dots that are appropriate for single-particle tracking measurements with NIR emission.

Dennis, Allison M. [Los Alamos National Laboratory; Mangum, Benjamin D. [Los Alamos National Laboratory; Piryatinski, Andrei [Los Alamos National Laboratory; Park, Young-Shin [Los Alamos National Laboratory; Htoon, Han [Los Alamos National Laboratory; Hollingsworth, Jennifer A. [Los Alamos National Laboratory

2012-06-21T23:59:59.000Z

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221

An intentionally positioned (In,Ga)As quantum dot in a micron sized light emitting diode  

SciTech Connect

We have integrated individual (In,Ga)As quantum dots (QDs) using site-controlled molecular beam epitaxial growth into the intrinsic region of a p-i-n junction diode. This is achieved using an in situ combination of focused ion beam prepatterning, annealing, and overgrowth, resulting in arrays of individually electrically addressable (In,Ga)As QDs with full control on the lateral position. Using microelectroluminescence spectroscopy we demonstrate that these QDs have the same optical quality as optically pumped Stranski-Krastanov QDs with random nucleation located in proximity to a doped interface. The results suggest that this technique is scalable and highly interesting for different applications in quantum devices.

Mehta, M.; Michaelis de Vasconcellos, S.; Zrenner, A.; Meier, C. [Department of Physics and Center for Optoelectronics and Photonics Paderborn (CeOPP), University of Paderborn, Warburger Street 100, 33098 Paderborn (Germany); Reuter, D.; Wieck, A. D. [Applied Solid State Physics, Ruhr-University of Bochum, Universitaetsstr. 150, 44780 Bochum (Germany)

2010-10-04T23:59:59.000Z

222

Heat induced nanoforms of zinc oxide quantum dots and their characterization  

SciTech Connect

In our studies we observed heat induced phase transitions of Zinc oxide quantum dots at 60, 200, 360 and 400 Degree-Sign C, where all the transitions were irreversible except the transition at 60 Degree-Sign C which wasa reversible one. The phase transition at 60 Degree-Sign C indicated a heat induced conformational change which was supported here by studying polarizing micrographs of ZnO quantum dots thin film. The X-ray diffraction studies of the sample fired at different temperatures as indicated by the thermal analysis were performed in order to understand the changes occurred due to transitions. The study also indicated a new and simple approach to develop ZnO nanorods by just thermal decomposition of the ZnO quantum dots firing in furnace at 200 Degree-Sign C with 2h soaking. In order to have a proper insight of the structural changes we performed scanning electron microscopy. Optical characterization was done by UV-Vis and fluorescence spectrophotometer.

Dey, Anindita [Jadavpur University, Physics Department (India); Basu, Ruma [Jogamaya Devi College, Physics department (India); Das, Sukhen, E-mail: sukhendasju@gmail.com; Nandy, Papiya [Jadavpur University, Physics Department (India)

2012-02-15T23:59:59.000Z

223

A Large Blue Shift of the Biexciton State in Tellurium Doped CdSe Colloidal Quantum Dots  

E-Print Network (OSTI)

The exciton-exciton interaction energy of Tellurium doped CdSe colloidal quantum dots is experimentally investigated. The dots exhibit a strong Coulomb repulsion between the two excitons, which results in a huge measured biexciton blue shift of up to 300 meV. Such a strong Coulomb repulsion implies a very narrow hole wave function localized around the defect, which is manifested by a large Stokes shift. Moreover, we show that the biexciton blue shift increases linearly with the Stokes shift. This result is highly relevant for the use of colloidal QDs as optical gain media, where a large biexciton blue shift is required to obtain gain in the single exciton regime. The progress in chemical synthesis of colloidal quantum dots, provides a way to produce high quantum yield nanocrystals out of a variety of substances, and allows control over their size, shape and composition. Because of the strong charge confinement within the dots, their electronic excitation

Assaf Avidan; Dan Oron

2008-01-01T23:59:59.000Z

224

Micro-Photoluminescence Characterization of Low Density Droplet GaAs Quantum Dots for Single Photon Sources  

Science Conference Proceedings (OSTI)

The GaAs quantum dots in AlGaAs barriers were grown by droplet epitaxy, emitting around 700 nm in wavelength which is compatible with low cost Si based detectors. The excitation power dependent and time resolved micro-photoluminescence measurements identified optical characteristics of exciton and biexciton states which are attributed to good quantum confinements in GaAs QDs.

Ha, S.-K.; Song, J. D.; Lim, J. Y.; Choi, W. J.; Han, I. K.; Lee, J. I. [Nano Convergence Devices Center, KIST, Seoul 136-791 (Korea, Republic of); Bounouar, S.; Donatini, F.; Dang, L. S.; Poizat, J. P. [CEA/CNRS/UJF team 'Nanophysics and semiconductors', Institute Neel/CNRS-UJF, 38042 Grenoble (France); Kim, J. S. [Department of Physics, Yeungnam University, Gyeongsan 712-749 (Korea, Republic of)

2011-12-23T23:59:59.000Z

225

The influence of external fields on the energy of two interacting electrons in a quantum dot  

SciTech Connect

In this paper, the effects of both an external electric field and an external magnetic field on the energy of two interacting electrons in a two-dimensional parabolic quantum dot are investigated for various quantum states (n,|m|) in the framework of the asymptotic iteration method. It is seen that the energy eigenvalues increase monotonically with increasing electric and magnetic field strengths in the weak- and strong-field regimes. However, the behavior is slightly different in the two regimes. Whereas the energy values increase linearly in the low-electric-field regime, they increase much more than linearly in the strong-field regime. This paper demonstrates that it is possible to obtain the energy eigenvalues of two electrons in a two-dimensional parabolic quantum dot not only for cases with and without an electric field and with and without a magnetic field, but also for cases where magnetic and electric fields (either strong or weak) are present simultaneously. - Highlights: Black-Right-Pointing-Pointer The energy eigenvalues of two electrons in a 2D quantum dot in external electric and magnetic fields are discussed. Black-Right-Pointing-Pointer The effects of the fields on the energies are obtained for strong and weak fields. Black-Right-Pointing-Pointer The energies increase monotonically with increasing field. Black-Right-Pointing-Pointer The increase in the energies in weak fields has a different behavior from that in strong fields. Black-Right-Pointing-Pointer The method used here is very efficient for discovering the effects of external fields on different states.

Soylu, A., E-mail: asimsoylu@gmail.com

2012-12-15T23:59:59.000Z

226

The Hybridization of CdSe/ZnS Quantum Dot on InGaN Light-Emitting Diodes for Color Conversion  

Science Conference Proceedings (OSTI)

We have demonstrated the fabrication and characterization of hybrid CdSe/ZnS quantum dot (QD)-InGaN blue LEDs. The chemically synthesized red light (lambda = 623 nm) QD solutions with different concentrations were dropped onto the blue InGaN LEDs with ... Keywords: CdSe/ZnS quantum dots, CdSe/ZnS quantum dots (QDs), InGaN quantum well and hybrid LEDs, InGaN quantum well and hybrid light-emitting diodes

Ying-Chih Chen; Chun-Yuan Huang; Yan-Kuin Su; Wen-Liang Li; Chia-Hsien Yeh; Yu-Cheng Lin

2008-07-01T23:59:59.000Z

227

Exciton fine-structure splitting of telecom wavelength single quantum dots: statistics and external strain tuning  

E-Print Network (OSTI)

In a charge tunable device, we investigate the fine structure splitting of neutral excitons in single long-wavelength (1.1\\mu m response of the splitting to the external strain, including positive and negative tuning slopes, different tuning ranges, and linear and parabolic dependencies, indicating that these physical parameters depend strongly on the unique microscopic structure of the individual quantum dot. To better understand the experimental results, we apply a phenomenological model describing the exciton polarization and fine-structure splitting under uniaxial strain. The model predicts that, with an increased experimental strain tuning range, the fine-structure can be effectively canceled for select telecom wavelength dots using uniaxial strain. These results are promising for the generation of on-demand entangled photon pairs at telecom wavelengths.

Luca Sapienza; Ralph N. E. Malein; Christopher E. Kuklewicz; Peter E. Kremer; Kartik Srinivasan; Andrew Griffiths; Edmund Clarke; Ming Gong; Richard J. Warburton; Brian D. Gerardot

2013-03-05T23:59:59.000Z

228

Quantitative Excited State Spectroscopy of a Single InGaAs Quantum Dot Molecule through Multi-million Atom Electronic Structure Calculations  

E-Print Network (OSTI)

Atomistic electronic structure calculations are performed to study the coherent inter-dot couplings of the electronic states in a single InGaAs quantum dot molecule. The experimentally observed excitonic spectrum [12] is quantitatively reproduced, and the correct energy states are identified based on a previously validated atomistic tight binding model. The extended devices are represented explicitly in space with 15 million atom structures. An excited state spectroscopy technique is presented in which the externally applied electric field is swept to probe the ladder of the electronic energy levels (electron or hole) of one quantum dot through anti-crossings with the energy levels of the other quantum dot in a two quantum dot molecule. This technique can be applied to estimate the spatial electron-hole spacing inside the quantum dot molecule as well as to reverse engineer quantum dot geometry parameters such as the quantum dot separation. Crystal deformation induced piezoelectric effects have been discussed in the literature as minor perturbations lifting degeneracies of the electron excited (P and D) states, thus affecting polarization alignment of wave function lobes for III-V Heterostructures such as single InAs/GaAs quantum dots. In contrast this work demonstrates the crucial importance of piezoelectricity to resolve the symmetries and energies of the excited states through matching the experimentally measured spectrum in an InGaAs quantum dot molecule under the influence of an electric field. Both linear and quadratic piezoelectric effects are studied for the first time for a quantum dot molecule and demonstrated to be indeed important. The net piezoelectric contribution is found to be critical in determining the correct energy spectrum, which is in contrast to recent studies reporting vanishing net piezoelectric contributions.

Muhammad Usman; Yui-Hong Matthias Tan; Hoon Ryu; Shaikh S. Ahmed; Hubert Krenner; Timothy B. Boykin; Gerhard Klimeck

2010-08-18T23:59:59.000Z

229

Measurement of electronic splitting in PbS quantum dots by two-dimensional nonlinear spectroscopy  

Science Conference Proceedings (OSTI)

Quantum dots exhibit rich and complex electronic structure that makes them ideal for studying the basic physics of semiconductors in the intermediate regime between bulk materials and single atoms. The remarkable nonlinear optical properties of these nanostructures make them strong candidates for photonics applications. Here, we experimentally probe changes in the fine structure on ultrafast timescales of a colloidal solution of PbS quantum dots through their nonlinear optical response despite extensive inhomogeneous spectral broadening. Using continuum excitation and detection, we observe electronic coupling between nearly degenerate exciton states split by intervalley scattering at low exciton occupancy and a sub-100 fs frequency shift presumably due to phonon-assisted transitions. At high excitation intensities, we observe multi-exciton effects and sharp absorbance bands indicative of exciton-exciton coupling. Our experiments directly probe the nonlinear optical response of nearly degenerate quantum confined nanostructures with femtosecond temporal resolution despite extensive line broadening caused by the finite size distribution found in colloidal solutions.

Harel, E.; Rupich, S. M.; Schaller, R. D.; Talapin, D. V.; Engel, G. S. (Center for Nanoscale Materials); (Univ. of Chicago); (Northwestern Univ.)

2012-01-01T23:59:59.000Z

230

The control of size and areal density of InAs self-assembled quantum dots in selective area molecular beam epitaxy on GaAs (001) surface  

Science Conference Proceedings (OSTI)

The growth of InAs quantum dots (QDs) on GaAs (001) substrates by selective area molecular beam epitaxy (SA-MBE) with dielectric mask is investigated. The GaAs polycrystals on the mask, which is formed during growth due to low GaAs selectivity between ... Keywords: InAs quantum dots, Molecular beam epitaxy, Selective area epitaxy

J. C. Lin; P. W. Fry; R. A. Hogg; M. Hopkinson; I. M. Ross; A. G. Cullis; R. S. Kolodka; A. I. Tartakovskii; M. S. Skolnick

2006-12-01T23:59:59.000Z

231

The effect of encapsulation on the morphology and chemical composition of InAs/GaAs quantum dots grown by molecular beam epitaxy  

Science Conference Proceedings (OSTI)

In order to fabricate an effective device structure based on InAs quantum dots (QDs), the QD layers must be encapsulated within a matrix that has a wider band gap. This encapsulation is usually achieved by the overgrowth of GaAs. Coherent strained InAs/GaAs ... Keywords: encapsulation, indium arsenide, quantum dots, transmission electron microscopy

D. Zhi; M. Wei; R. E. Dunin-Borkowski; P. A. Midgley; D. W. Pashley; T. S. Jones; B. A. Joyce; P. F. Fewster; P. J. Goodhew

2004-06-01T23:59:59.000Z

232

Photoluminescence Study of Interdot Carrier Transfer on Strain-relaxed InAs Quantum Dots  

SciTech Connect

Photoluminescence (PL) properties of the strain relaxed InAs quantum dots (QDs) are studied as a function of temperature from 10 to 300 K. Two groups of QDs induced by strain relaxation are observed in the PL spectra. The PL peak position of the relaxed (non-relaxed) QDs locates at a higher (lower) energy. TEM image prove QDs are distributed into two groups and indicate the QDs relax the strain by diffusing indium to GaAs. In the 120-200 K temperature range, there are abnormal temperature behaviors attributed to the carrier transfer from the relaxed to non-relaxed QDs.

Chiang, Chen-Hao; Chang, You-Cheng; Hsieh, Meng-Chien; Yang, Cheng-Hong; Wang, Jia-Feng; Chen, Jenn-Fang [Department of Electrophysics, National Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu 30050, Taiwan (China); Wu, Yue-Han; Chang, Li [Department of Materials Science and Engineering, National Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu 30050, Taiwan (China)

2011-12-23T23:59:59.000Z

233

Determination of the Exciton Binding Energy in CdSe Quantum Dots  

Science Conference Proceedings (OSTI)

The exciton binding energy (EBE) in CdSe quantum dots (QDs) has been determined using x-ray spectroscopy. Using x-ray absorption and photoemission spectroscopy, the conduction band (CB) and valence band (VB) edge shifts as a function of particle size have been determined and combined to obtain the true band gap of the QDs (i.e. without and exciton). These values can be compared to the excitonic gap obtained using optical spectroscopy to determine the EBE. The experimental EBE results are compared with theoretical calculations on the EBE and show excellent agreement.

Meulenberg, R; Lee, J; Wolcott, A; Zhang, J; Terminello, L; van Buuren, T

2009-10-27T23:59:59.000Z

234

An oleic acid-capped CdSe quantum-dot sensitized solar cell  

SciTech Connect

In this letter, we report an oleic acid (OA)-capped CdSe quantum-dot sensitized solar cell (QDSSC) with an improved performance. The TiO{sub 2}/OA-CdSe photoanode in a two-electrode device exhibited a photon-to-current conversion efficiency of 17.5% at 400 nm. At AM1.5G irradiation with 100 mW/cm{sup 2} light intensity, the QDSSCs based on OA-capped CdSe showed a power conversion efficiency of about 1%. The function of OA was to increase QD loading, extend the absorption range and possibly suppress the surface recombination.

Chen Jing [School of Electronic Science and Engineering, Southeast University, Nanjing 210096 (China); School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore); Song, J. L.; Deng, W. Q. [Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Science, Nanyang Technological University, Singapore 637616 (Singapore); Sun, X. W. [School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore); Institute of Microelectronics, 11 Science Park Road, Science Park II, Singapore 117685 (Singapore); Jiang, C. Y. [Institute of Microelectronics, 11 Science Park Road, Science Park II, Singapore 117685 (Singapore); Lei, W. [School of Electronic Science and Engineering, Southeast University, Nanjing 210096 (China); Huang, J. H.; Liu, R. S. [Department of Chemistry, National Taiwan University, Taipei 106, Taiwan (China)

2009-04-13T23:59:59.000Z

235

Direct Patterning of CdSe Quantum Dots into Sub-100 nm Structures  

SciTech Connect

Ordered, two-dimensional cadmium selenide (CdSe) arrays have been fabricated on indium-doped tin oxide (ITO) electrodes using the pattern replication in nonwetting templates (PRINT) process. CdSe quantum dots (QDs) with an average diameter of 2.7 nm and a pyridine surface ligand were used for patterning. The PRINT technique utilizes a perfluoropolyether (PFPE) elastomeric mold that is tolerant of most organic solvents, thus allowing solutions of CdSe QDs in 4-picoline to be used for patterning without significant deformation of the mold. Nanometer-scale diffraction gratings have been successfully replicated with CdSe QDs.

Hampton, Meredith J.; Templeton, Joseph L.; DeSimone, Joseph M.

2010-01-01T23:59:59.000Z

236

Polarization-Driven Stark Shifts in Quantum Dot Luminescence from Single CdSe/oligo-PPV Nanoparticles  

Science Conference Proceedings (OSTI)

We demonstrate polarization-induced spectral shifts and associated linearly polarized absorption and emission in single CdSe/oligo-(phenylene vinylene) (CdSe/OPV) nanoparticles. A mechanism for these observations is presented in which charge separation from photoexcited ligands results in a significant Stark distortion of the quantum dot electron/hole wavefunctions. This distortion results in an induced linear polarization and an associated red shift in band-edge photoluminescence. These studies suggest the use of single quantum dots as local charge mobility probes.

Early, K. T.; Sudeep, P. K.; Emrick, Todd; Barnes, M. D.

2010-01-01T23:59:59.000Z

237

Controllable coupling and quantum correlation dynamics of two double quantum dots coupled via a transmission line resonator  

E-Print Network (OSTI)

We propose a theoretical scheme to generate a controllable and switchable coupling between two double-quantum-dot (DQD) spin qubits by using a transmission line resonator (TLR) as a bus system. We study dynamical behaviors of quantum correlations described by entanglement correlation (EC) and discord correlation (DC) between two DQD spin qubits when the two spin qubits and the TLR are initially prepared in $X$-type quantum states and a coherent state, respectively. We demonstrate that in the EC death regions there exist DC stationary states in which the stable DC amplification or degradation can be generated during the dynamical evolution. It is shown that these DC stationary states can be controlled by initial-state parameters, the coupling, and detuning between qubits and the TLR. We reveal the full synchronization and anti-synchronization phenomena in the EC and DC time evolution, and show that the EC and DC synchronization and anti-synchronization depends on the initial-state parameters of the two DQD spin qubits. These results shed new light on dynamics of quantum correlations.

Qin-Qin Wu; Qing-Shou Tan; Le-Man Kuang

2010-11-25T23:59:59.000Z

238

"All-Inorganic, Efficient Photovoltaic Solid State Devices Utilizing Semiconducting Colloidal Nanocrystal Quantum Dots"  

DOE Green Energy (OSTI)

We demonstrated robust colloidal quantum dot (QD) photovoltaics with high internal quantum efficiencies. In our structures, device durability is derived from use of all-inorganic atmospherically-stable semiconducting metal-oxide films together with QD photoreceptors. We have shown that both QD and metal-oxide semiconducting films and contacts are amenable to room temperature processing under minimal vacuum conditions, enabling large area processing of PV structures of high internal efficiency. We generated the state of the art devices with power conversion efficiency of more than 4%, and have shown that efficiencies as high as 9% are achievable in the near-term, and as high as 17% in the long-term.

Vladimir Bulovic and Moungi Bawendi

2011-09-30T23:59:59.000Z

239

Quantum Dot Light Enhancement Substrate for OLED Solid-State Lighting  

SciTech Connect

With DOE Award No. DE-EE00000628, QD Vision developed and demonstrated a cost-competitive solution for increasing the light extraction efficiency of OLEDs with efficient and stable color rendering index (CRI) for solid state lighting (SSL). Solution processable quantum dot (QD) films were integrated into OLED ITO-glass substrates to generate tunable white emission from blue emitting OLED) devices as well as outcouple light from the ITO film. This QD light-enhancement substrate (QD-LED) technology demonstrated a 60% increase in OLED forward light out-coupling, a value which increases to 76% when considering total increase in multi-directional light output. The objective for the first year was an 80% increase in light output. This project seeks to develop and demonstrate a cost-competitive solution for realizing increased extraction efficiency organic light emitting devices (OLEDs) with efficient and stable color rendering index (CRI) for SSL. Solution processible quantum dot (QD) films will be utilized to generate tunable white emission from blue emitting phosphorescent OLED (Ph-OLED) devices.

James Perkins; Matthew Stevenson; Gagan Mahan; Seth Coe-Sullivan; Peter Kazlas

2011-01-21T23:59:59.000Z

240

Quantum dots for tracking cellular transport of lectin-functionalized nanoparticles  

SciTech Connect

Successful drug delivery by functionalized nanocarriers largely depends on their efficient intracellular transport which has not yet been fully understood. We developed a new tracking technique by encapsulating quantum dots into the core of wheat germ agglutinin-conjugated nanoparticles (WGA-NP) to track cellular transport of functionalized nanocarriers. The resulting nanoparticles showed no changes in particle size, zeta potential or biobinding activity, and the loaded probe presented excellent photostability and tracking ability. Taking advantage of these properties, cellular transport profiles of WGA-NP in Caco-2 cells was demonstrated. The cellular uptake begins with binding of WGA to its receptor at the cell surface. The subsequent endocytosis happened in a cytoskeleton-dependent manner and by means of clathrin and caveolae-mediated mechanisms. After endosome creating, transport occurs to both trans-Golgi and lysosome. Our study provides new evidences for quantum dots as a cellular tracking probe of nanocarriers and helps understand intracellular transport profile of lectin-functionalized nanoparticles.

Gao Xiaoling [Department of Pharmaceutics, School of Pharmacy, Fudan University, Shanghai 200032 (China); Department of Pharmacology, Institute of Medical Sciences, Shanghai Jiaotong University School of Medicine, Shanghai 200025 (China); Wang Tao [Surface Physics Laboratory (National Key Laboratory), Physics Department, Fudan University, Shanghai 200433 (China); Wu Bingxian; Chen Jun [Department of Pharmaceutics, School of Pharmacy, Fudan University, Shanghai 200032 (China); Chen Jiyao [Surface Physics Laboratory (National Key Laboratory), Physics Department, Fudan University, Shanghai 200433 (China); Yue Yang; Dai Ning [National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China); Chen Hongzhuan [Department of Pharmacology, Institute of Medical Sciences, Shanghai Jiaotong University School of Medicine, Shanghai 200025 (China)], E-mail: yaoli@shsmu.edu.cn; Jiang Xinguo [Department of Pharmaceutics, School of Pharmacy, Fudan University, Shanghai 200032 (China)], E-mail: xgjiang@shmu.edu.cn

2008-12-05T23:59:59.000Z

Note: This page contains sample records for the topic "quantum dot tracers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

Photoinduced Surface Oxidation and Its Effect on the Exciton Dynamics of CdSe Quantum Dots  

DOE Green Energy (OSTI)

With increased interest in semiconductor nanoparticles for use in quantum dot solar cells there comes a need to understand the long-term photostability of such materials. Colloidal CdSe quantum dots (QDs) were suspended in toluene and stored in combinations of light/dark and N{sub 2}/O{sub 2} to simulate four possible benchtop storage environments. CdSe QDs stored in a dark, oxygen-free environment were observed to better retain their optical properties over the course of 90 days. The excited state lifetimes, determined through femtosecond transient absorption spectroscopy, of air-equilibrated samples exposed to light exhibit a decrease in average lifetime (0.81 ns) when compared to samples stored in a nitrogen/dark environment (8.3 ns). A photoetching technique commonly used for controlled reduction of QD size was found to induce energetic trap states to CdSe QDs and accelerate the rate of electron-hole recombination. X-ray absorption near edge structure (XANES) analysis confirms surface oxidation, the extent of which is shown to be dependent on the thickness of the ligand shell.

Hines, Douglas A.; Becker, Matthew A.; Kamat, Prashant V. (Notre)

2012-11-14T23:59:59.000Z

242

Investigation of the Emission Properties of Quantum Dot-thermoresponsive Polymer Nanocomposite Hydrogels with Temperature  

E-Print Network (OSTI)

This thesis presents a novel method for the preparation of quantum dot-thermoresponsive polymer nanocomposite hydrogels. The quantum dots (QD’s) were synthesized in a microwave reactor using a high temperature organometallic synthesis procedure. The initial hydrophobic surface layer on the QD’s was coated with an amphiphilic polymer to enable phase transfer from non-polar solvent to water followed by physical immobilization of the QD’s in the thermoresponsive polymer hydrogel by photopolymerization. Their temperature dependent emission properties were investigated as a function of concentration of the incorporated QD’s. The resultant temperature dependent changes in the position of the peak emission wavelength of the QD-polymer nanocomposite hydrogels were found to be due to the change in the physical environment causing increased interaction between the embedded amphiphilic polymer coated QD’s and/or due to aggregation of QD’s. This change in peak emission position was found to be reversible in the temperature range from 29 to 37 °C.

Juriani, Ameet Rajkumar

2010-05-01T23:59:59.000Z

243

Dynamics of nuclear polarization in InGaAs quantum dots in a transverse magnetic field  

SciTech Connect

The time-resolved Hanle effect is examined for negatively charged InGaAs/GaAs quantum dots. Experimental data are analyzed by using an original approach to separate behavior of the longitudinal and transverse components of nuclear polarization. This made it possible to determine the rise and decay times of each component of nuclear polarization and their dependence on transverse magnetic field strength. The rise and decay times of the longitudinal component of nuclear polarization (parallel to the applied field) were found to be almost equal (approximately 5 ms). An analysis of the transverse component of nuclear polarization shows that the corresponding rise and decay times differ widely and strongly depend on magnetic field strength, increasing from a few to tens of milliseconds with an applied field between 20 and 100 mT. Current phenomenological models fail to explain the observed behavior of nuclear polarization. To find an explanation, an adequate theory of spin dynamics should be developed for the nuclear spin system of a quantum dot under conditions of strong quadrupole splitting.

Verbin, S. Yu., E-mail: syuv54@mail.ru; Gerlovin, I. Ya.; Ignatiev, I. V., E-mail: ivan_ignatiev@mail.ru; Kuznetsova, M. S.; Cherbunin, R. V. [St. Petersburg State University, Spin Optics Laboratory (Russian Federation); Flisinski, K.; Yakovlev, D. R.; Bayer, M. [Technische Universitaet Dortmund (Germany)

2012-04-15T23:59:59.000Z

244

Revolutionary Method for Increasing the Efficiency of White Light Quantum Dot LEDs  

SciTech Connect

Covering a light-emitting diode (LED) with quantum dots (QDs) can produce a broad spectrum of white light. However, current techniques for applying QDs to LEDs suffer from a high density of defects and a non-uniform distribution of QDs, which respec-tively diminish the efficiency and quality of emitted light. Oak Ridge National Laboratory (ORNL) has the unique capability to thermally anneal QD structures at extremely high power densities for very short durations. This process, called pulse thermal proc-essing (PTP), reduces the number of point defects while main-taining the size and shape of the original QD nanostructure. Therefore, the efficiency of the QD wavelength conversion layer is improved without altering the emission spectrum defined by the size distribution of the quantum dot nanoparticles. The cur-rent research uses a thermal model to predict annealing tempera-tures during PTP and demonstrates up to a 300% increase in pho-toluminescence for QDs on passive substrates

Duty, Chad E [ORNL; Bennett, Charlee J C [ORNL; Sabau, Adrian S [ORNL; Jellison Jr, Gerald Earle [ORNL; Boudreaux, Philip R [ORNL; Walker, Steven C [ORNL; Ott, Ronald D [ORNL

2011-01-01T23:59:59.000Z

245

TiO2 Nanotubes with a ZnO Thin Energy Barrier for Improved Current Efficiency of CdSe Quantum-Dot-Sensitized Solar Cells  

Science Conference Proceedings (OSTI)

This paper reports the formation of a thin ZnO energy barrier between a CdSe quantum dot (Q dots) sensitizer and TiO{sub 2} nanotubes (TONTs) for improved current efficiency of Q dot-sensitized solar cells. The formation of a ZnO barrier between TONTs and the Q dot sensitizer increased the short-circuit current under illumination and also reduced the dark current in a dark environment. The power conversion efficiency of Q dot-sensitized TONT solar cells increased by 25.9% in the presence of the ZnO thin layer due to improved charge-collecting efficiency and reduced recombination.

Lee, W.; Kang, S. H.; Kim, J. Y.; Kolekar, G. B.; Sung, Y. E.; Han, S. H.

2009-01-01T23:59:59.000Z

246

Energy distributions of carriers in quantum dot laser structures Simon Osborne, Peter Blood, Peter Smowton, Julie Lutti  

E-Print Network (OSTI)

Energy distributions of carriers in quantum dot laser structures Simon Osborne, Peter Blood, Peter probability distribution in energy with a global Fermi level2, possibly because of the strong interaction under quasi-equilibrium conditions. An understanding of the energy distribution of electrons

New Mexico, University of

247

Annealing effect on photovoltaic performance of CdSe quantum-dots-sensitized TiO2 nanorod solar cells  

Science Conference Proceedings (OSTI)

Large area rutile TiO2 nanorod arrays were grown on F:SnO2 (FTO) conductive glass using a hydrothermal method at low temperature. CdSe quantum dots (QDs) were deposited onto single-crystalline TiO2 nanorod arrays by a ...

Yitan Li, Lin Wei, Ruizi Zhang, Yanxue Chen, Jun Jiao

2012-01-01T23:59:59.000Z

248

Green route synthesis of high quality CdSe quantum dots for applications in light emitting devices  

SciTech Connect

Investigation was made on light emitting diodes fabricated using CdSe quantum dots. CdSe quantum dots were synthesized chemically using olive oil as the capping agent, instead of toxic phosphine. Room temperature photoluminescence investigation showed sharp 1st excitonic emission peak at 568 nm. Bi-layer organic/inorganic (P3HT/CdSe) hybrid light emitting devices were fabricated by solution process. The electroluminescence study showed low turn on voltage ({approx}2.2 V) .The EL peak intensity was found to increase by increasing the operating current. - Graphical abstract: Light emitting diode was fabricated using CdSe quantum dots using olive oil as the capping agent, instead of toxic phosphine. Bi-layer organic/inorganic (P3HT/CdSe) hybrid light emitting device shows strong electroluminescence in the range 630-661 nm. Highlights: Black-Right-Pointing-Pointer CdSe Quantum dots were synthesized using olive oil as the capping agent. Black-Right-Pointing-Pointer Light emitting device was fabricated using CdSe QDs/P3HT polymer heterojunction. Black-Right-Pointing-Pointer The I-V characteristics study showed low turn on voltage at {approx}2.2 V. Black-Right-Pointing-Pointer The EL peak intensity increases with increasing the operating current.

Bera, Susnata, E-mail: susnata.bera@gmail.com [Department of Physics and Meteorology, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India); Singh, Shashi B. [Department of Physics and Meteorology, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India); Ray, S.K., E-mail: physkr@phy.iitkgp.ernet.in [Department of Physics and Meteorology, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India)

2012-05-15T23:59:59.000Z

249

Measuring charge trap occupation and energy level in CdSe/ZnS quantum dots using a scanning tunneling microscope  

E-Print Network (OSTI)

We use a scanning tunneling microscope to probe single-electron charging phenomena in individual CdSe/ZnS (core/shell) quantum dots (QDs) at room temperature. The QDs are deposited on top of a bare Au thin film and form a ...

Bulovic, Vladimir

250

Process-Dependent Properties in Colloidally Synthesized “Giant” Core/Shell Nanocrystal Quantum Dots  

SciTech Connect

Due to their characteristic bright and stable photoluminescence, semiconductor nanocrystal quantum dots (NQDs) have attracted much interest as efficient light emitters for applications from single-particle tracking to solid-state lighting. Despite their numerous enabling traits, however, NQD optical properties are frustratingly sensitive to their chemical environment, exhibit fluorescence intermittency ('blinking'), and are susceptible to Auger recombination, an efficient nonradiative decay process. Previously, we showed for the first time that colloidal CdSe/CdS core/shell nanocrystal quantum dots (NQDs) comprising ultrathick shells (number of shell monolayers, n, > 10) grown by protracted successive ionic layer adsorption and reaction (SILAR) leads to remarkable photostability and significantly suppressed blinking behavior as a function of increasing shell thickness. We have also shown that these so-called 'giant' NQDs (g-NQDs) afford nearly complete suppression of non-radiative Auger recombination, revealed in our studies as long biexciton lifetimes and efficient multiexciton emission. The unique behavior of this core/shell system prompted us to assess correlations between specific physicochemical properties - beyond shell thickness - and functionality. Here, we demonstrate the ability of particle shape/faceting, crystalline phase, and core size to determine ensemble and single-particle optical properties (quantum yield/brightness, blinking, radiative lifetimes). Significantly, we show how reaction process parameters (surface-stabilizing ligands, ligand:NQD ratio, choice of 'inert' solvent, and modifications to the SILAR method itself) can be tuned to modify these function-dictating NQD physical properties, ultimately leading to an optimized synthetic approach that results in the complete suppression of blinking. We find that the resulting 'guiding principles' can be applied to other NQD compositions, allowing us to achieve non-blinking behavior in the near-infrared. Lastly, in addition to realizing novel light-emission properties by refining nanoscale architectures at the single-NQD level, we also investigate collective properties by assembling our core/shell NQDs into larger scale arrays.

Hollingsworth, Jennifer A. [Los Alamos National Laboratory; Ghosh, Yagnaseni [Los Alamos National Laboratory; Dennis, Allison M. [Los Alamos National Laboratory; Mangum, Benjamin D. [Los Alamos National Laboratory; Park, Young-Shin [Los Alamos National Laboratory; Kundu, Janardan [Los Alamos National Laboratory; Htoon, Han [Los Alamos National Laboratory

2012-06-07T23:59:59.000Z

251

Effect of the nonlinear saturation of the gain on the peak modulation frequency in lasers based on self-assembled quantum dots  

SciTech Connect

Peak modulation frequency of lasers based on self-organized quantum dots is calculated taking into account the effect of nonlinear gain saturation. Because of a large nonlinear gain coefficient and a reduction in the differential gain with increasing optical losses, the peak modulation frequency is attained for an optimum loss level that is significantly lower than the saturated optical gain in the active region. For lasers based on multiply stacked arrays of quantum dots, the peak modulation frequency first increases with increasing number of quantum-dot layers before leveling off, with the limiting value being inversely proportional to the nonlinear gain coefficient.

Zhukov, A. E., E-mail: zhukov@beam.ioffe.ru; Arakcheeva, E. M. [Russian Academy of Sciences, St. Petersburg Academic University, Nanotechnology Research and Education Center (Russian Federation); Gordeev, N. Yu. [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation); Zubov, F. I.; Kryzhanovskaya, N. V. [Russian Academy of Sciences, St. Petersburg Academic University, Nanotechnology Research and Education Center (Russian Federation); Maximov, M. V. [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation); Savelyev, A. V. [Russian Academy of Sciences, St. Petersburg Academic University, Nanotechnology Research and Education Center (Russian Federation)

2011-07-15T23:59:59.000Z

252

A InGaN/GaN quantum dot green ({lambda}=524 nm) laser  

SciTech Connect

The characteristics of self-organized InGaN/GaN quantum dot lasers are reported. The laser heterostructures were grown on c-plane GaN substrates by plasma-assisted molecular beam epitaxy and the laser facets were formed by focused ion beam etching with gallium. Emission above threshold is characterized by a peak at 524 nm (green) and linewidth of 0.7 nm. The lowest measured threshold current density is 1.2 kA/cm{sup 2} at 278 K. The slope and wall plug efficiencies are 0.74 W/A and {approx}1.1%, respectively, at 1.3 kA/cm{sup 2}. The value of T{sub 0}=233 K in the temperature range of 260-300 K.

Zhang Meng; Banerjee, Animesh; Lee, Chi-Sen; Hinckley, John M.; Bhattacharya, Pallab [Department of Electrical Engineering and Computer Science, Center for Nanoscale Photonics and Spintronics, University of Michigan, Ann Arbor, Michigan 48109-2122 (United States)

2011-05-30T23:59:59.000Z

253

Binary Heterogeneous Superlattices Assembled from Quantum Dots and Gold Nanoparticles with DNA  

SciTech Connect

Controllable assembly of three-dimensional (3D) superlattices composed of different types of nanoscale objects opens new opportunities for material fabrication. Herein we show the successful assembly of heterogeneous 3D structures from gold nanoparticles (AuNPs) and quantum dots (QDs) using DNA encoding. By applying synchrotron-based small-angle X-ray scattering, we found that AuNPs and QDs are positioned in a body-centered cubic lattice, while each particle type, AuNP and QD, is arranged in a simple-cubic manner. Our studies demonstrate a route for assembly of integrated heterogeneous 3D structures from different nano-objects by DNA-encoded interactions.

D Sun; O Gang

2011-12-31T23:59:59.000Z

254

Advanced method for increasing the efficiency of white light quantum dot LEDs  

SciTech Connect

Covering a light-emitting diode (LED) with quantum dots (QDs) can produce a broad spectrum of white light. However, current techniques for applying QDs to LEDs suffer from a high density of defects and a non-uniform distribution of QDs, which, respectively, diminish the efficiency and quality of emitted light. Oak Ridge National Laboratory (ORNL) has the unique capability to thermally anneal QD structures at extremely high power densities for very short durations. This process, called pulse thermal processing (PTP), reduces the number of point defects while maintaining the size and shape of the original QD nanostructure. Therefore, the efficiency of the QD wavelength conversion layer is improved without altering the emission spectrum defined by the size distribution of theQD nanoparticles. The current research uses a thermal model to predict annealing temperatures during PTP and demonstrates up to a 300% increase in photoluminescence for QDs on passive substrates.

Duty, Chad E [ORNL; Bennett, Charlee J C [ORNL; Sabau, Adrian S [ORNL; Jellison Jr, Gerald Earle [ORNL; Boudreaux, Philip R [ORNL; Walker, Steven C [ORNL; Ott, Ronald D [ORNL

2011-01-01T23:59:59.000Z

255

Numerical Simulation of Annealing of CdSe Quantum Dots for White Light LEDs  

Science Conference Proceedings (OSTI)

The pulsed thermal processing (PTP) of CdSe Quantum Dots (QD) using a High Density plasma arc lamp. The single layer of CdSe QD was deposited on sapphire and was encapsulated in an alumina matrix. A computational methodology is proposed to understand the energy transport and annealing of QD material for solid-state lighting applications. It was found that the energy balance in the system was affected by the QD. The QD monolayer of spheres was found to alter the total reflectivity, even though the energy absorbed in QD was relatively small. The numerical simulations can be an effective tool to predict the narrow range of processing parameters and dramatically reduce expensive trial-and-error procedures while enabling the enhanced properties of nanostructured materials to be realized.

Sabau, Adrian S [ORNL; Duty, Chad E [ORNL; Ott, Ronald D [ORNL; Jellison Jr, Gerald Earle [ORNL

2008-01-01T23:59:59.000Z

256

Periodic alignment of Si quantum dots on hafnium oxide coated single wall carbon nanotubes  

SciTech Connect

We demonstrate a bottom up approach for the aligned epitaxial growth of Si quantum dots (QDs) on one-dimensional (1D) hafnium oxide (HfO{sub 2}) ridges created by the growth of HfO{sub 2} thin film on single wall carbon nanotubes. This growth process creates a high strain 1D ridge on the HfO{sub 2} film, which favors the formation of Si seeds over the surrounding flat HfO{sub 2} area. Periodic alignment of Si QDs on the 1D HfO{sub 2} ridge was observed, which can be controlled by varying different growth conditions, such as growth temperature, growth time, and disilane flow rate.

Olmedo, Mario; Martinez-Morales, Alfredo A.; Ozkan, Mihrimah; Liu Jianlin [Department of Electrical Engineering, University of California, Riverside, California 92521 (United States); Liu Gang; Lau, C.N. [Department of Physics and Astronomy, University of California, Riverside, California 92521 (United States); Yengel, Emre; Ozkan, Cengiz S. [Department of Mechanical Engineering, University of California, Riverside, California 92521 (United States)

2009-03-23T23:59:59.000Z

257

Excitation Power Dependence Of Photoluminescence From GaAs Quantum Dot Prepared By Droplet Epitaxy Method  

Science Conference Proceedings (OSTI)

GaAs quantum dot (QD) was grown by droplet epitaxy (DE) method and the excitation power dependence of photoluminescence (PL) were carried out. To investigate the effect of annealing temperature on QDs optical properties, the two step RTA process was carried out in a various temperature range from 800 to 1000 deg. C. As the thermal annealing temperature increases, the PL peak position is blue-shifted due to the change of the composition and size distribution of QDs, and the highest PL intensity is observed at the sample annealed at 900 deg. C. The integrated PL intensity (I{sub PL}) is plotted against the excitation density in a log-log scale and the slope was calculated.

Choi, H. Y.; Kim, D. Y.; Cho, M. Y.; Kim, G. S.; Jeon, S. M.; Yim, K. G.; Kim, M. S.; Leem, J. Y. [Department of Nano Systems Engineering, Center for Nano Manufacturing, Inje University, Gimhae (Korea, Republic of); Lee, D. Y. [Epi-manufacturing Technology, Samsung LED Co., Ltd., Suwon (Korea, Republic of); Kim, J. S. [Division of Advanced Materials Engineering, Chonbuk National University, Jeonju (Korea, Republic of); Kim, J. S. [Department of Physics, Yeungnam University, Gyeongsan (Korea, Republic of); Son, J. S. [Department of Visual Optics, Kyungwoon University, Gumi (Korea, Republic of); Lee, J. I. [Advanced Instrument Technology Center, Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of)

2011-12-23T23:59:59.000Z

258

Charge Trapping in Bright and Dark States of Coupled PbS Quantum Dot Films  

DOE Green Energy (OSTI)

Analysis of photoluminescence (PL) from chemically treated lead sulfide (PbS) quantum dot (QD) films versus temperature reveals the effects of QD size and ligand binding on the motion of carriers between bright and dark trap states. For strongly coupled QDs, the PL exhibits temperature-dependent quenching and shifting consistent with charges residing in a shallow exponential tail of quasi-localized states below the band gap. The depth of the tail varies from 15 to 40 meV, similar to or smaller than exponential band tail widths measured for polycrystalline Si. The trap state distribution can be manipulated with QD size and surface treatment, and its characterization should provide a clearer picture of charge separation and percolation in disordered QD films than what currently exists.

Gao, J.; Johnson, J. C.

2012-04-24T23:59:59.000Z

259

Carrier dynamics and activation energy of CdTe quantum dots in a Cd{sub x}Zn{sub 1-x}Te quantum well  

SciTech Connect

We investigate the optical properties of CdTe quantum dots (QDs) in a Cd{sub 0.3}Zn{sub 0.7}Te quantum well (QW) grown on GaAs (100) substrates. Carrier dynamics of CdTe/ZnTe QDs and quantum dots-in-a-well (DWELL) structure is studied using time-resolved photoluminescence (PL) measurements, which show the longer exciton lifetime of the DWELL structure. The activation energy of the electrons confined in the DWELL structure, as obtained from the temperature-dependent PL spectra, was also higher than that of electrons confined in the CdTe/ZnTe QDs. This behavior is attributed to the better capture of carriers into QDs within the surrounding QW.

Han, W. I.; Lee, J. H.; Yu, J. S.; Choi, J. C. [Department of Physics, Yonsei University, Wonju 220-710 (Korea, Republic of); Lee, H. S. [Advanced Photonics Research Institute, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of)

2011-12-05T23:59:59.000Z

260

Thin Film Solar Cells Derived from Sintered Semiconductor Quantum Dots: Cooperative Research and Development Final Report, CRADA number CRD-07-00226  

Science Conference Proceedings (OSTI)

The NREL/Evident team will develop techniques to fabricate thin film solar cells where the absorption layers comprising the solar cells are derived from sintered semiconductor quantum dots.

Ginley, D. S.

2010-07-01T23:59:59.000Z

Note: This page contains sample records for the topic "quantum dot tracers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

Theoretical And Experimental Studies Of The Effects Of Rapid Thermal Annealing In GaAs/AlGaAs Quantum Dots Grown By Droplet Epitaxy  

Science Conference Proceedings (OSTI)

We fabricated low-density GaAs/AlGaAs quantum dots for single photon source by droplet epitaxy. We investigated the emission energies of the dots and underlying superlattice by using photoluminescence and cathodoluminescence measurements. By forming a mesa etched structure, we distinguished the transitions from the superlattice and the dots. And we calculated the diffusion length in this system from the peak shift of the superlattice, and applied the diffusion to the dots to investigate the emission energy shift of the QDs.z

Moon, P. [Nano Convergence Devices Center, Korea Institute of Science and Technology, Seoul (Korea, Republic of); School of Materials Science, Japan Advanced Institute of Science and Technology, Ishikawa (Japan); Ha, S.-K.; Song, J. D.; Lim, J. Y.; Choi, W. J.; Han, I. K.; Lee, J. I. [Nano Convergence Devices Center, Korea Institute of Science and Technology, Seoul (Korea, Republic of); Bounouar, S.; Donatini, F.; Dang, L. S.; Poizat, J. P. [CEA/CNRS/UJF team 'Nanophysics and semiconductors', Institute Neel/CNRS-UJF, Grenoble (France); Kim, J. S. [Department of Physics, Yeungnam University, Gyeonsan (Korea, Republic of)

2011-12-23T23:59:59.000Z

262

Ultra-shallow quantum dots in an undoped GaAs/AlGaAs two-dimensional electron gas  

SciTech Connect

We report quantum dots fabricated on very shallow 2-dimensional electron gases, only 30 nm below the surface, in undoped GaAs/AlGaAs heterostructures grown by molecular beam epitaxy. Due to the absence of dopants, an improvement of more than one order of magnitude in mobility (at 2 Multiplication-Sign 10{sup 11} cm{sup -2}) with respect to doped heterostructures with similar depths is observed. These undoped wafers can easily be gated with surface metallic gates patterned by e-beam lithography, as demonstrated here from single-level transport through a quantum dot showing large charging energies (up to 1.75 meV) and excited state energies (up to 0.5 meV).

Mak, W. Y.; Sfigakis, F.; Beere, H. E.; Farrer, I.; Griffiths, J. P.; Jones, G. A. C.; Ritchie, D. A. [Cavendish Laboratory, University of Cambridge, Cambridge (United Kingdom)] [Cavendish Laboratory, University of Cambridge, Cambridge (United Kingdom); Das Gupta, K. [Cavendish Laboratory, University of Cambridge, Cambridge (United Kingdom) [Cavendish Laboratory, University of Cambridge, Cambridge (United Kingdom); Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India); Klochan, O.; Hamilton, A. R. [School of Physics, University of New South Wales, Sydney (Australia)] [School of Physics, University of New South Wales, Sydney (Australia)

2013-03-11T23:59:59.000Z

263

Coherent rotations of a single spin-based qubit in a single quantum dot at fixed Zeeman energy  

E-Print Network (OSTI)

Coherent rotations of single spin-based qubits may be accomplished electrically at fixed Zeeman energy with a qubit defined solely within a single electrostatically-defined quantum dot; the $g$-factor and the external magnetic field are kept constant. All that is required to be varied are the voltages on metallic gates which effectively change the shape of the elliptic quantum dot. The pseudospin-1/2 qubit is constructed from the two-dimensional $S=1/2$, $S_z=-1/2$ subspace of three interacting electrons in a two-dimensional potential well. Rotations are created by altering the direction of the pseudomagnetic field through changes in the shape of the confinement potential. By deriving an exact analytic solution to the long-range Coulomb interaction matrix elements, we calculate explicitly the range of magnitudes and directions the pseudomagnetic field can take. Numerical estimates are given for {GaAs}.

Jordan Kyriakidis; Stephen J. Penney

2004-07-06T23:59:59.000Z

264

Kondo Resonance in a Mesoscopic Ring Coupled to a Quantum Dot: Exact Results for the Aharonov-Bohm-Casher Effects  

Science Conference Proceedings (OSTI)

We study the persistent currents induced by both the Aharonov-Bohm and Aharonov-Casher effects in a one-dimensional mesoscopic ring coupled to a sidebranch quantum dot at Kondo resonance. For privileged values of the Aharonov-Bohm-Casher fluxes, the problem can be mapped onto an integrable model, exactly solvable by a Bethe ansatz. In the case of a pure magnetic Aharonov-Bohm flux, we find that the presence of the quantum dot has no effect on the persistent current. In contrast, the Kondo resonance interferes with the spin-dependent Aharonov-Casher effect to induce a current which, in the strong-coupling limit, is independent of the number of electrons in the ring.

Eckle, H.-P.; Johannesson, H.; Stafford, C. A.

2001-07-02T23:59:59.000Z

265

Tuning of the optical properties of [11k] grown InAs quantum dots by the capping layer  

Science Conference Proceedings (OSTI)

A three-dimensional k.p calculation including strain and piezoelectricity shows that for large [11k] grown QD, the presence of an (In,Ga)As capping layer leads to an increase of the optical transition energy, in contrast to the expected decrease. The ... Keywords: 71.35.Ji, 71.70.Gm, 73.21.La, 78.20.Ls, Capping, High index surfaces, K.p theory, Quantum dots

V. Mlinar; F. M. Peeters

2008-03-01T23:59:59.000Z

266

An improved pyrolysis route to synthesize carbon-coated CdS quantum dots with fluorescence enhancement effect  

SciTech Connect

Well-dispersed carbon-coated CdS (CdS-C) quantum dots were successfully prepared via the improved pyrolysis of bis(1-dodecanethiol)-cadmium(II) under nitrogen atmosphere. This simple method effectively solved the sintered problem resulted from conventional pyrolysis process. The experimental results indicated that most of the as-prepared nanoparticles displayed well-defined core-shell structures. The CdS cores with diameter of {approx}5 nm exhibited hexagonal crystal phase, the carbon shells with thickness of {approx}2 nm acted as a good dispersion medium to prevent CdS particles from aggregation, and together with CdS effectively formed a monodisperse CdS-Carbon nanocomposite. This composite presented a remarkable fluorescence enhancement effect, which indicated that the prepared nanoparticles might be a promising photoresponsive material or biosensor. This improved pyrolysis method might also offer a facile way to prepare other carbon-coated semiconductor nanostructures. - Graphical abstract: We demonstrated a facile approach to synthesize well-dispersed carbon-coated CdS quantum dots. The as-prepared nanoparticles presented remarkable fluorescence enhancement effect. Highlights: > Carbon-coated CdS quantum dots were synthesized by an one-step pyrolysis method. > Well-dispersed CdS-carbon nanoparticles were obtained by an acid treatment process. > As-prepared nanoparticles presented remarkable fluorescence enhancement effect.

Zhang Kejie [Key Laboratory for Soft Chemistry and Functional Materials of Ministry Education, Nanjing University of Science and Technology, Nanjing 210094 (China); Liu Xiaoheng, E-mail: xhliu@mail.njust.edu.cn [Key Laboratory for Soft Chemistry and Functional Materials of Ministry Education, Nanjing University of Science and Technology, Nanjing 210094 (China)

2011-10-15T23:59:59.000Z

267

Structure of droplet-epitaxy-grown InAs/GaAs quantum dots  

Science Conference Proceedings (OSTI)

We have used a direct x-ray phasing method, coherent Bragg rod analysis, to obtain sub-angstrom resolution electron density maps of the InAs/GaAs dot system. The dots were grown by the droplet heteroepitaxy (DHE) technique and their structural and compositional properties are compared with those of dots grown by the strain-driven Stranski-Krastanov method. Our results show that the Ga diffusion into the DHE-grown dots is somewhat larger; however, other characteristics such as the composition of the dots uppermost layers, the interlayer spacing, and the bowing of the atomic layers are similar.

Cohen, Eyal; Yochelis, Shira; Westreich, Ohad; Shusterman, Sergey; Kumah, Divine P.; Clarke, Roy; Yacoby, Yizhak; Paltiel, Yossi (Michigan); (Hebrew); (Soreq NRC, Israel)

2011-09-06T23:59:59.000Z

268

NIST Quantum Physics Division - 1998  

Science Conference Proceedings (OSTI)

... QUANTUM PHYSICS DIVISION. Fluorescence Trajectory of a Single 30 Angstrom Radius CdSe Quantum Dot. The quantum ...

269

Long Electron-Hole Separation of ZnO-CdS Core-Shell Quantum Dots  

DOE Green Energy (OSTI)

The tunability of electronic and optical properties of semiconductor nanocrystal quantum dots (QDs) has been an important subject in nanotechnology. While control of the emission property of QDs in wavelength has been studied extensively, control of the emission lifetime of QDs has not been explored in depth. In this report, ZnO-CdS core-shell QDs were synthesized in a two-step process, in which we initially synthesized ZnO core particles, and then stepwise slow growth of CdS shells followed. The coating of a CdS shell on a ZnO core increased the exciton lifetime more than 100 times that of the core ZnO QD, and the lifetime was further extended as the thickness of shell increased. This long electron-hole recombination lifetime is due to a unique staggered band alignment between the ZnO core and CdS shell, so-called type II band alignment, where the carrier excitation holes and electrons are spatially separated at the core and shell, and the exciton lifetime becomes extremely sensitive to the thickness of the shell. Here, we demonstrated that the emission lifetime becomes controllable with the thickness of the shell in ZnO-CdS core-shell QDs. The longer excitonic lifetime of type II QDs could be beneficial in fluorescence-based sensors, medical imaging, solar cells photovoltaics, and lasers.

Xu, F.; Volkov, V.; Zhu, Y.; Bai, H.; Rea, A.; Valappil, N.V.; Su, W.; Gao, X.; Kuskovsky, I.L.; Matsui, H.

2009-10-19T23:59:59.000Z

270

Observation of Band Alignment Transition in InAs/GaAsSb Quantum Dots by Photoluminescence  

Science Conference Proceedings (OSTI)

The band alignment of InAs quantum dots (QDs) embedded in GaAsSb barriers with various Sb compositions is investigated by photoluminescence (PL) measurements. InAs/GaAsSb samples with 13% and 15% Sb compositions show distinct differences in emission spectra as the PL excitation power increases. Whilst no discernible shift is seen for the 13% sample, a blue-shift of PL spectra following a 1/3 exponent of the excitation power is observed for the 15% sample suggesting a transition from a type I to type II band alignment. Time-resolved PL data show a significant increase in carrier lifetime as the Sb composition increases between 13% and 15% implying that the transformation from a type I to type II band alignment occurs between 13% and 15% Sb compositions. These results taken together lead to the conclusion that a zero valence band offset (VBO) can be achieved for the InAs/GaAsSb system in the vicinity of 14% Sb composition.

Ban, K. Y.; Kuciauskas, D.; Bremner, S. P.; Honsberg, C. B.

2012-05-15T23:59:59.000Z

271

Optical stability of shape-engineered InAs/InAlGaAs quantum dots  

SciTech Connect

The optical properties of shape-engineered InAs/InAlGaAs quantum dots (SEQDs) were investigated by temperature-dependent and excitation-power-dependent photoluminescence (PL) spectroscopy and compared with those of the conventionally grown InAs QDs (CQDs). The emission wavelength of the InAs/InAlGaAs SEQDs at 240 K was redshifted by 18 nm from that at 15 K, which was relatively smaller than that of the InAs CQDs (97 nm). The PL yield at 240 K was reduced to 1/86 and 1/65 of that measured at 15 K for the InAs CQDs and the InAs/InAlGaAs SEQDs, respectively. The emission wavelength for the InAs CQDs was blueshifted by 76 nm with increasing excitation power from 0.56 to 188 mW, compared to only by 7 nm for the InAs/InAlGaAs SEQDs. These results indicated that the InAs/InAlGaAs SEQDs were optically more stable than the InAs CQDs mainly due to the enhancement of the carrier confinement in the vertical direction and the improvement in the size uniformity.

Yang, Youngsin; Jo, Byounggu; Kim, Jaesu; Lee, Cheul-Ro; Kim, Jin Soo [Division of Advanced Materials Engineering, Research Center of Advanced Materials Development (RCAMD), Chonbuk National University, Jeonju, Chonbuk 561-756 (Korea, Republic of); Oh, Dae Kon [Electronics and Telecommunication Research Institute (ETRI), Daejeon 305-350 (Korea, Republic of); Kim, Jong Su [Advanced Photonics Research Institute, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of); Leem, Jae-Young [School of Nano Engineering, Inje University, Gimhae 621-749 (Korea, Republic of)

2009-03-01T23:59:59.000Z

272

Intermixing of InGaAs/GaAs quantum wells and quantum dots using sputter-deposited silicon oxynitride capping layers  

SciTech Connect

Various approaches can be used to selectively control the amount of intermixing in III-V quantum well and quantum dot structures. Impurity-free vacancy disordering is one technique that is favored for its simplicity, however this mechanism is sensitive to many experimental parameters. In this study, a series of silicon oxynitride capping layers have been used in the intermixing of InGaAs/GaAs quantum well and quantum dot structures. These thin films were deposited by sputter deposition in order to minimize the incorporation of hydrogen, which has been reported to influence impurity-free vacancy disordering. The degree of intermixing was probed by photoluminescence spectroscopy and this is discussed with respect to the properties of the SiO{sub x}N{sub y} films. This work was also designed to monitor any additional intermixing that might be attributed to the sputtering process. In addition, the high-temperature stress is known to affect the group-III vacancy concentration, which is central to the intermixing process. This stress was directly measured and the experimental values are compared with an elastic-deformation model.

McKerracher, Ian; Fu Lan; Hoe Tan, Hark; Jagadish, Chennupati [Department of Electronic Materials Engineering, Research School of Physics and Engineering, Australian National University, Canberra, Australian Capital Territory 0200 (Australia)

2012-12-01T23:59:59.000Z

273

Probing into hybrid organic-molecule and InAs quantum-dots nanosystem with multistacked dots-in-a-well units  

SciTech Connect

Hybridizing air-stable organic-molecules with advanced III-V semiconductor quantum-dots (QDs) structures can be utilized to create a new generation of biochemical sensing devices. In order to enhance their optical performances, the active regions in these QDs structures commonly consist of multistacked dots-in-a-well (DWELL) units. The effects of grafted molecules on the performances of the QDs structures with multistacked DWELLs, however, still remain unclear. Here, we show the significant improvements in the optical properties of InAs QDs in a hybrid nanosystem obtained by grafting biocompatible diazonium salt compound (amine donor) atop InAs QDs structure. Since its interface between the QDs structure and molecular monolayer retains an uncontaminated and non-oxidized condition, the nanosystem is an ideal platform to study the intrinsic properties of charge-carrier transport inside the system. Because of the complexity of the energy-levels in the QDs structure due to the existing surface QDs and DWELLs, selective excitation wavelengths (400, 633, and 885 nm, respectively) with different photo-energies are used to exactly analyze the complete charging mechanism in these QDs. A clear view of charge-carrier transfer inside the nanosystem is revealed by employing photoluminescence technique under selective-wavelength excitations. The present work provides new quantitative evidences for exploiting inorganic QDs applications in complex biological systems.

Chen Miaoxiang [Department of Micro- and Nano technology, Technical University of Denmark, Orsteds Plads, 2800 Kgs. Lyngby (Denmark); Kobashi, Kazufumi [Nanotube Research Center, National Institute of Advanced Industrial Science and Technology (AIST), AIST Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565 (Japan)

2012-09-15T23:59:59.000Z

274

GaSb/GaAs quantum dot formation and demolition studied with cross-sectional scanning tunneling microscopy  

Science Conference Proceedings (OSTI)

We present a cross-sectional scanning tunneling microscopy study of GaSb/GaAs quantum dots grown by molecular beam epitaxy. Various nanostructures are observed as a function of the growth parameters. During growth, relaxation of the high local strain fields of the nanostructures plays an important role in their formation. Pyramidal dots with a high Sb content are often accompanied by threading dislocations above them. GaSb ring formation is favored by the use of a thin GaAs first cap layer and a high growth temperature of the second cap layer. At these capping conditions, strain-driven Sb diffusion combined with As/Sb exchange and Sb segregation remove the center of a nanostructure, creating a ring. Clusters of GaSb without a well defined morphology also appear regularly, often with a highly inhomogeneous structure which is sometimes divided up in fragments.

Smakman, E. P.; Garleff, J. K.; Rambabu, P.; Koenraad, P. M. [Department of Applied Physics, Eindhoven University of Technology, Eindhoven 5612 AZ (Netherlands); Young, R. J.; Hayne, M. [Department of Physics, Lancaster University, Lancaster LA1 4YB (United Kingdom)

2012-04-02T23:59:59.000Z

275

The Study On The Physical Properties Of CdS Quantum Dots Synthesized By Ligand Exchange in Cd{sup 2+}-thiol Aqueous Solutions  

SciTech Connect

We synthesized CdS quantum dots in aqueous medium using three thiolate-ligands, 2-mercaptoethanol (2ME), 3-mercaptopropanoic acid (MPA) and dimercaprol (BAL) by ligand exchange method. With a fixed concentration of thiols, the absorption edge of the quantum dots formed shifted towards shorter wavelength, as to the decreasing of a concentration of CdCl{sub 2}. When a concentration of CdCl{sub 2} and thiol was same, band gap energies and average sizes of the quantum dots were shown to be 2.65 eV, 3.26 nm for MPA, 2.84 eV, 3.16 nm for 2 ME and 3.16 eV, 1.81 nm for BAL, respectively. PL spectra analysis shows that as the decrease in molar concentration of CdCl{sub 2}, emission peak shifted towards shorter wavelength.

Ha, S. Y.; Yoo, D. S.; Kim, I. G.; Choo, M. S.; Kim, G. W.; Lee, E. S. [Department of Physics, Changwon National University, Changwon 641-773 (Korea, Republic of); Lee, B. C. [Laboratory for Quantum Optics, Korea Atomic Energy Research Institute, Daejon 306-600 (Korea, Republic of)

2011-12-23T23:59:59.000Z

276

Coupling of single InGaAs quantum dots to the plasmon resonance of a metal nanocrystal  

Science Conference Proceedings (OSTI)

The authors report the coupling of single InGaAs quantum dots (QDs) to the surface plasmon resonance of a metal nanocrystal. Clear enhancement of the photoluminescence (PL) in the spectral region of the surface plasmon resonance is observed which splits up into distinct emission lines from single QDs in micro-PL. The hybrid metal-semiconductor structure is grown by molecular beam epitaxy on GaAs (100) utilizing the concept of self-organized anisotropic strain engineering for realizing ordered arrays with nanometer-scale precise positioning of the metal nanocrystals with respect to the QDs.

Urbanczyk, A.; Hamhuis, G. J.; Noetzel, R. [Department of Applied Physics, COBRA Research Institute on Communication Technology, Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands)

2010-07-26T23:59:59.000Z

277

Pulsed Electrical Spin Injection into InGaAs Quantum Dots: Studies of the Electroluminescence Polarization Dynamics  

SciTech Connect

We present time-resolved studies of the spin polarization dynamics during and after initialization through pulsed electrical spin injection into InGaAs quantum dots embedded in a p-i-n-type spin-injection light-emitting diode. Experiments are performed with pulse widths in the nanosecond range and a time-resolved single photon counting setup is used to detect the subsequent electroluminescence. We find evidence that the achieved spin polarization shows an unexpected temporal behavior, attributed mainly to many-carrier and non-equilibrium effects in the device.

Asshoff, P.; Loeffler, W.; Fluegge, H.; Zimmer, J.; Mueller, J.; Westenfelder, B.; Hu, D. Z.; Schaadt, D. M.; Kalt, H.; Hetterich, M. [Institut fuer Angewandte Physik and DFG Center for Functional Nanostructures (CFN), Universitaet Karlsruhe, 76131 Karlsruhe (Germany)

2010-01-04T23:59:59.000Z

278

Surface Enhanced Raman Spectroscopy of Pyridine on CdSe/ZnBeSe Quantum Dots Grown by MBE  

SciTech Connect

Using Surface Enhanced Raman Spectroscopy (SERS), we observed Raman enhancements (104-105) for pyridine molecules adsorbed on a II-VI semiconductor CdSe/ZnBeSe sample of uncapped self-assembled quantum dots produced by molecular beam epitaxy. When a monolayer of pyridine is adsorbed on these structures, excitation at 488 nm produces intense Raman spectra a very large enhancement of the a1, b1 and b2 modes. This indicates the presence of charge-transfer as a contributor to the enhacement.

Livingstone, Richard [City College of New York, New York, NY (United States)

2010-08-06T23:59:59.000Z

279

Control of growth and the processes of energy transfer from CdSe quantum dots for Nd{sup 3+} ions in a vitreous system: Thermal annealing time  

SciTech Connect

The authors report clear evidence of radiative and nonradiative energy transfer from CdSe quantum dots to Nd{sup 3+} ions in a glass system synthesized by melting method. An efficient control of energy transfer can be obtained by controlling the mean radius of the CdSe quantum dots. Increase of about 100% of the near infrared Nd{sup 3+} emission ({sup 4}F{sub 3/2}{yields}{sup 4}I{sub 9/2}) was observed as a function of thermal annealing time.

Dantas, N. O.; Serqueira, E. O. [Laboratorio de Novos Materiais Isolantes e Semicondutores-LNMIS, Instituto de Fisica, Universidade Federal de Uberlandia, 38400-902 Uberlandia, Minas Gerais (Brazil); Anjos, V.; Bell, M. J. V. [Grupo de Espectroscopia de Materiais, Departamento de Fisica, Universidade Federal de Juiz de Fora, 36036-330 Juiz de Fora, Minas Gerais (Brazil)

2012-09-17T23:59:59.000Z

280

Thermal stability of the deep ultraviolet emission from AlGaN/AlN Stranski-Krastanov quantum dots  

Science Conference Proceedings (OSTI)

We report on the structural and optical properties of AlGaN/AlN quantum dot (QD) superlattices synthesized by plasma-assisted molecular-beam epitaxy. Modifying the composition and geometry of the QDs, the peak emission wavelength can be shifted from 320 nm to 235 nm while keeping the internal quantum efficiency larger than 30%. The efficient carrier confinement is confirmed by the stability of the photoluminescence (PL) intensity and decay time, from low temperature up to 100 K. Above this threshold, the PL intensity decreases and the radiative lifetime increases due to carrier thermalization. We also identified the intraband electronic transition between the ground level of the conduction band and the first excited state confined along the growth axis (s-p{sub z}).

Himwas, C.; Songmuang, R.; Le Si Dang [CEA-CNRS Group 'Nanophysique et Semiconducteurs,' Institut Neel-CNRS, 25 rue des Martyrs, 38042 Grenoble Cedex 9 (France); Bleuse, J.; Monroy, E. [CEA-CNRS Group 'Nanophysique et Semiconducteurs,' INAC-SP2M, CEA-Grenoble, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France); Rapenne, L.; Sarigiannidou, E. [INP-Grenoble/Minatec, 3 parvis Louis Neel BP257, 38016 Grenoble (France)

2012-12-10T23:59:59.000Z

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281

Effect of electron-nuclear spin interactions on electron-spin qubits localized in self-assembled quantum dots  

E-Print Network (OSTI)

The effect of electron-nuclear spin interactions on qubit operations is investigated for a qubit represented by the spin of an electron localized in a self-assembled quantum dot. The localized electron wave function is evaluated within the atomistic tight-binding model. The magnetic field generated by the nuclear spins is estimated in the presence of an inhomogeneous environment characterized by a random nuclear spin configuration, by the dot-size distribution, by alloy disorder, and by interface disorder. Due to these inhomogeneities, the magnitude of the nuclear magnetic field varies from one qubit to another by the order of 100 G, 100 G, 10 G, and 0.1 G, respectively. The fluctuation of the magnetic field causes errors in exchange operations due to the inequality of the Zeeman splitting between two qubits. We show that the errors can be made lower than the quantum error threshold if an exchange energy larger than 0.1 meV is used for the operation.

Seungwon Lee; Paul von Allmen; Fabiano Oyafuso; Gerhard Klimeck; K. Birgitta Whaley

2004-03-17T23:59:59.000Z

282

Influence of Internal Fields on the Electronic Structure in Self-Assembled InAs/GaAs Quantum Dots  

E-Print Network (OSTI)

Built-in electrostatic fields in Zincblende quantum dots originate mainly from - (1) the fundamental crystal atomicity and the interfaces between two dissimilar materials, (2) the strain relaxation, and (3) the piezoelectric polarization. In this paper, using the atomistic NEMO 3-D simulator, we study the origin and nature of the internal fields in InAs/GaAs quantum dots with three different geometries, namely, box, dome, and pyramid. We then calculate and delineate the impact of the internal fields in the one-particle electronic states in terms of shift in the conduction band energy states, anisotropy and non-degeneracy in the P level, and formation of mixed excited bound states. Models and approaches used in this study are as follow: (1) Valence force field (VFF) with strain-dependent Keating potentials for atomistic strain relaxation; (2) 20-band nearest-neighbor sp3d5s* tight-binding model for the calculation of single-particle energy states; and (3) For piezoelectricity, for the first time within the fra...

Islam, Sharnali; Ahmed, Shaikh

2010-01-01T23:59:59.000Z

283

Piezoelectric InAs (211)B quantum dots grown by molecular beam epitaxy: Structural and optical properties  

Science Conference Proceedings (OSTI)

The structural and optical properties of piezoelectric (211)B InAs nanostructures grown by molecular beam epitaxy are systematically investigated as a function of the various growth parameters. Depending on the specific growth conditions, we show that the InAs nanostructures take the form of a quantum dot (QD) or a quantum dash, their height ranges between 2 and 20 nm, and their density varies from a few times 10{sup 8} cm{sup -2} all the way up to a few times 10{sup 10} cm{sup -2}. The (211)B QDs are characterized by large aspect ratios, which are compatible with a truncated pyramid morphology. By analyzing the QD emission spectrum, we conclude that only small size QDs, with heights less than 3 nm, are optically active. This is consistent with high resolution transmission electron microscopy observations showing that large QDs contain misfit dislocations, whereas small QDs are dislocation-free. The formation of a two-dimensional wetting layer is observed optically, and its thickness is determined to be between 0.30 and 0.39 nm. Finally, the large blueshift in the QD emission observed with increasing excitation power represents a clear evidence of the strong built-in piezoelectric field present in these dots.

Dialynas, G. E. [Department of Physics, University of Crete, P.O. Box 2208, 71003 Heraklion (Greece); Kalliakos, S.; Xenogianni, C. [Department of Materials Science and Technology, University of Crete, P.O. Box 2208, 71003 Heraklion (Greece); Androulidaki, M. [Microelectronics Research Group, IESL-FORTH, P.O. Box 1385, 71110 Heraklion (Greece); Kehagias, T.; Komninou, P. [Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Savvidis, P. G.; Pelekanos, N. T. [Department of Materials Science and Technology, University of Crete, P.O. Box 2208, 71003 Heraklion (Greece); Microelectronics Research Group, IESL-FORTH, P.O. Box 1385, 71110 Heraklion (Greece); Hatzopoulos, Z. [Department of Physics, University of Crete, P.O. Box 2208, 71003 Heraklion (Greece); Microelectronics Research Group, IESL-FORTH, P.O. Box 1385, 71110 Heraklion (Greece)

2010-11-15T23:59:59.000Z

284

Surface X-Ray Diffraction Results on the III-V Droplet Heteroepitaxy Growth Process for Quantum Dots: Recent Understanding and Open Questions  

SciTech Connect

In recent years, epitaxial growth of self-assembled quantum dots has offered a way to incorporate new properties into existing solid state devices. Although the droplet heteroepitaxy method is relatively complex, it is quite relaxed with respect to the material combinations that can be used. This offers great flexibility in the systems that can be achieved. In this paper we review the structure and composition of a number of quantum dot systems grown by the droplet heteroepitaxy method, emphasizing the insights that these experiments provide with respect to the growth process. Detailed structural and composition information has been obtained using surface X-ray diffraction analyzed by the COBRA phase retrieval method. A number of interesting phenomena have been observed: penetration of the dots into the substrate ('nano-drilling') is often encountered; interdiffusion and intermixing already start when the group III droplets are deposited, and structure and composition may be very different from the one initially intended.

Cohen, Eyal; Elfassy, Naomi; Koplovitz, Guy; Yochelis, Shira; Shusterman, Sergey; Kumah, Divine P.; Yacoby, Yizhak; Clarke, Roy; Paltiel, Yossi (Michigan); (Hebrew)

2012-04-24T23:59:59.000Z

285

Rapid and Sensitive Detection of Protein Biomarker Using a Portable Fluorescence Biosensor based on Quantum Dots and a Lateral Flow Test Strip  

Science Conference Proceedings (OSTI)

A portable fluorescence biosensor with rapid and ultrasensitive response for trace protein has been built up with quantum dots and lateral flow test strip. The superior signal brightness and high photostability of quantum dots are combined with the promising advantages of lateral flow test strip and resulted in high sensitivity, selectivity and speedy for protein detection. Nitrated ceruloplasmin, a significant biomarker for cardiovascular disease, lung cancer and stress response to smoking, was used as model protein to demonstrate the good performances of this proposed Qdot-based lateral flow test strip. Quantitative detection of nitrated ceruloplasmin was realized by recording the fluorescence intensity of quantum dots captured on the test line. Under optimal conditions, this portable fluorescence biosensor displays rapid responses for nitrated ceruloplasmin in wide dynamic range with a detection limit of 0.1ng/mL (S/N=3). Furthermore, the biosensor was successfully utilized for spiked human plasma sample detection with the concentration as low as 1ng/mL. The results demonstrate that the quantum dot-based lateral flow test strip is capable for rapid, sensitive, and quantitative detection of nitrated ceruloplasmin and hold a great promise for point-of-care and in field analysis of other protein biomarkers.

Li, Zhaohui; Wang, Ying; Wang, Jun; Tang, Zhiwen; Pounds, Joel G.; Lin, Yuehe

2010-08-15T23:59:59.000Z

286

CdSe quantum dots sensitized mesoporous TiO2 solar cells with CuSCN as solid-state electrolyte  

Science Conference Proceedings (OSTI)

Mesoporous TiO2 is functionalized by 3-mercaptopropyl trimethyoxysilane (MPTMS) to anchor CdSe quantum dots (QDs). The resulting TiO2/CdSe is combined with solid-state electrolyte (CuSCN) to form solar cells. It is found that the ...

Guanbi Chen; Lei Wang; Yu Zou; Xia Sheng; Hongjuan Liu; Xiaodong Pi; Deren Yang

2011-01-01T23:59:59.000Z

287

Percolation and excitonic luminescence in SiO{sub 2}/ZnO two-phase structures with a high density of quantum dots randomly distributed over a spherical surface  

Science Conference Proceedings (OSTI)

The results of studies of structures formed of silica (SiO{sub 2}) nanospheres and ZnO quantum dots randomly distributed over the nanosphere surface to cover an {approx}0.45 fraction of the surface area are given. Because of the large surface energy of the spheres, the quantum dots formed on their surface are shaped as disks, wherein charge carriers are influenced by the quantum-confinement effect despite the large disk radii. The disk height is calculated by the effective mass method. The height is found to be comparable with the diameter of excitons in bulk ZnO. Analysis of the optical spectra shows that, at the above-indicated surface area covered with quantum dots, excitons in the array of quantum dots are above the percolation level. The use of some concepts of the percolation theory and knowledge of the topological arrangement of the samples make it possible to obtain quantitative parameters that describe this phenomenon.

Bondar, N. V., E-mail: jbond@iop.kiev.ua [National Academy of Sciences of Ukraine, Institute of Physics (Ukraine)

2011-04-15T23:59:59.000Z

288

Temperature-dependent dynamical nuclear polarization bistabilities in double quantum dots in the spin-blockade regime  

E-Print Network (OSTI)

The interplay of dynamical nuclear polarization (DNP) and leakage current through a double quantum dot in the spin-blockade regime is analyzed. A finite DNP is built up due to a competition between hyperfine (HF) spin-flip transitions and another inelastic escape mechanism from the triplets, which block transport. We focus on the temperature dependence of the DNP for zero energy-detuning (i.e. equal electrostatic energy of one electron in each dot and a singlet in the right dot). Our main result is the existence of a transition temperature, below which the DNP is bistable, so a hysteretic leakage current versus external magnetic field B appears. This is studied in two cases: (i) Close to the crossing of the three triplet energy levels near B=0, where spin-blockade is lifted due to the inhomogeneity of the effective magnetic field from the nuclei. (ii) At higher B-fields, where the two spin-polarized triplets simultaneously cross two different singlet energy levels. We develop simplified models leading to different transition temperatures T_TT and T_ST for the crossing of the triplet levels and the singlet-triplet level crossings, respectively. We find T_TT analytically to be given solely by the HF couplings, whereas T_ST depends on various parameters and T_ST>T_TT. The key idea behind the existence of the transition temperatures at zero energy-detuning is the suppression of energy absorption compared to emission in the inelastic HF transitions. Finally, by comparing the rate equation results with Monte Carlo simulations, we discuss the importance of having both HF interaction and another escape mechanism from the triplets to induce a finite DNP.

Anders Mathias Lunde; Carlos López-Monís; Ioanna A. Vasiliadou; Luis L. Bonilla; Gloria Platero

2012-11-29T23:59:59.000Z

289

Laser irradiation effects on the CdTe/ZnTe quantum dot structure studied by Raman and AFM spectroscopy  

SciTech Connect

Micro-Raman spectroscopy has been applied to investigate the impact of laser irradiation on semiconducting CdTe/ZnTe quantum dots (QDs) structures. A reference sample (without dots) was also studied for comparison. Both samples were grown by molecular beam epitaxy technique on the p-type GaAs substrate. The Raman spectra have been recorded for different time of a laser exposure and for various laser powers. The spectra for both samples exhibit peak related to the localized longitudinal (LO) ZnTe phonon of a wavenumber equal to 210 cm{sup -1}. For the QD sample, a broad band corresponding to the LO CdTe phonon related to the QD-layer appears at a wavenumber of 160 cm{sup -1}. With increasing time of a laser beam exposure and laser power, the spectra get dominated by tellurium-related peaks appearing at wavenumbers around 120 cm{sup -1} and 140 cm{sup -1}. Simultaneously, the ZnTe surface undergoes rising damage, with the formation of Te aggregates at the pinhole edge as reveal atomic force microscopy observations. Local temperature of irradiated region has been estimated from the anti-Stokes/Stokes ratio of the Te modes intensity and it was found to be close or exceeding ZnTe melting point. Thus, the laser damage can be explained by the ablation process.

Zielony, E.; Placzek-Popko, E.; Henrykowski, A.; Gumienny, Z.; Kamyczek, P.; Jacak, J. [Institute of Physics, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw (Poland); Nowakowski, P.; Karczewski, G. [Institute of Physics, Polish Academy of Sciences, al. Lotnikow 32/46, 02-668 Warsaw (Poland)

2012-09-15T23:59:59.000Z

290

New Pathway Developed to Silicon Quantum Dot Devices (Fact Sheet), Highlights in Science, NREL (National Renewable Energy Laboratory)  

NLE Websites -- All DOE Office Websites (Extended Search)

Researchers create a way to prepare doped nanocrystal Researchers create a way to prepare doped nanocrystal solutions for solar thin films that are nontoxic and less expensive than heavy metal-based thin films. Scientists at the National Renewable Energy Laboratory (NREL) and the University of Minnesota have developed a method for preparing doped colloids (solutions) of silicon nanocrystals (NCs) as potential nontoxic infrared-absorbing and -emitting alternatives to metal chalcogenide quantum dots. Significant progress in the methods for preparing thin films of semiconductor NCs has recently led to very promising results in which metal chalcogenide (cadmium selenide, lead sulfide, etc.) NC thin films are used as the photoactive layer in solar cells, photodetectors, light-emitting diodes (LEDs), and related technologies.

291

Tunneling of conduction band electrons driven by a laser field in a double quantum dot: An open systems approach  

E-Print Network (OSTI)

In this paper, we investigate tunneling of conduction band electrons in a system of an asymmetric double quantum dot which interacts with an environment. First, we consider the case in which the system only interacts with the environment and demonstrate that as time goes to infinity they both reach an equilibrium, which is expected, and there is always a maximum and minimum for the populations of the states of the system. Then we investigate the case in which an external resonant optical pulse (a laser) is applied to the system interacting with the environment. However, in this case for different intensities we have different populations of the states in equilibrium and as the intensity of the laser gets stronger, the populations of the states in equilibrium approach the same constant.

B. Ahmadi; S. Salimi; A. S. Khorashad

2013-11-13T23:59:59.000Z

292

Impact of the Ga/In ratio on the N incorporation into (In,Ga)(As,N) quantum dots  

Science Conference Proceedings (OSTI)

In this work, we demonstrate the dependence of the nitrogen incorporation on the Ga/In content into (In,Ga)(As,N) quantum dots (QDs) grown on GaAs (100) by radio-frequency plasma assisted molecular beam epitaxy (MBE). Morphological analysis by atomic force microscopy and cross-sectional transmission electron microscopy, together with an estimation of the transition thickness, monitored in situ during the growth, predict a maximum in the N incorporation for 30% Ga content. This result is confirmed by photoluminescence measurements of the as-grown and post-growth annealed samples. We attribute this behavior to a trade off between two mechanisms depending on the Ga/In content: one related to the stability of the Ga-N bond, and the other related to the surface strain and/or In segregation.

Gargallo-Caballero, R.; Guzman, A.; Ulloa, J. M.; Hierro, A. [Instituto de Sistemas Optoelectronicos y Microtecnologia (ISOM)-Departamento de Ingenieria Electronica, ETSI Telecomunicacion, Universidad Politecnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid (Spain); Hopkinson, M. [Department of Electronic and Electrical Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom); Luna, E.; Trampert, A. [Paul Drude Institut fuer Festkoerperelektronik, Hausvogteiplatz 5-7, 10117 Berlin (Germany)

2012-04-15T23:59:59.000Z

293

Suppression of nuclear spin diffusion at a GaAs/AlGaAs interface measured with a single quantum dot nano-probe  

E-Print Network (OSTI)

Nuclear spin polarization dynamics are measured in optically pumped individual GaAs/AlGaAs interface quantum dots by detecting the time-dependence of the Overhauser shift in photoluminescence (PL) spectra. Long nuclear polarization decay times of ~ 1 minute have been found indicating inefficient nuclear spin diffusion from the GaAs dot into the surrounding AlGaAs matrix in externally applied magnetic field. A spin diffusion coefficient two orders lower than that previously found in bulk GaAs is deduced.

A. E. Nikolaenko; E. A. Chekhovich; M. N. Makhonin; I. W. Drouzas; A. B. Vankov; J. Skiba-Szymanska; M. S. Skolnick; P. Senellart; A. Lemaitre; A. I. Tartakovskii

2009-01-15T23:59:59.000Z

294

Study of Buried InAs Quantum Dots by Ballistic Electron Emission ...  

Science Conference Proceedings (OSTI)

About this Abstract. Meeting, Materials Science & Technology 2013. Symposium, MS&T'13 Poster Session. Presentation Title, Study of Buried InAs Quantum ...

295

Tracers and Tracer Interpretation | Open Energy Information  

Open Energy Info (EERE)

Tracers and Tracer Interpretation Tracers and Tracer Interpretation Jump to: navigation, search Contents 1 Geothermal Lab Call Projects for Tracers and Tracer Interpretation 2 Geothermal ARRA Funded Projects for Tracers and Tracer Interpretation Geothermal Lab Call Projects for Tracers and Tracer Interpretation Loading map... {"format":"googlemaps3","type":"ROADMAP","types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"limit":200,"offset":0,"link":"all","sort":[""],"order":[],"headers":"show","mainlabel":"","intro":"","outro":"","searchlabel":"\u2026

296

Quantum Processes and Metrology Group Homepage  

Science Conference Proceedings (OSTI)

... understanding needed to create nanooptics and quantum dot structures that ... We are developing quantum dots as reliable sources of single photons ...

2012-05-30T23:59:59.000Z

297

NIST Quantum Physics Division 1998 - Future Directions  

Science Conference Proceedings (OSTI)

... Single Molecule and Single Quantum Dot Confocal Microscopy. ... of individual dye molecules, green fluorescence protein, and CdSe quantum dots. ...

298

Direct Observation of sp-d Exchange Interactions in Colloidal Mn2+- and Co2+-Doped CdSe Quantum Dots  

SciTech Connect

The defining attribute of a diluted magnetic semiconductor (DMS) is the existence of dopant-carrier magnetic exchange interactions. In this letter, we report the first direct observation of such exchange interactions in colloidal doped CdSe nanocrystals. Doped CdSe quantum dots were synthesized by thermal decomposition of (Me4N)2[Cd4(SePh)10] in the presence of TMCl2 (TM2+ ) Mn2+ or Co2+) in hexadecylamine and were characterized by several analytical and spectroscopic techniques. Using magnetic circular dichroism spectroscopy, successful doping and the existence of giant excitonic Zeeman splittings in both Mn2+- and Co2+-doped wurtzite CdSe quantum dots are demonstrated unambiguously.

Archer, Paul I.; Santangelo, Steven A.; Gamelin, Daniel R.

2007-03-23T23:59:59.000Z

299

Infrared proximity sensor using organic light-emitting diode with quantum dots converter  

E-Print Network (OSTI)

-Chen Chen a , Han-Cheng Yeh b , Yu-Chiang Chao c , Hsin-Fei Meng c, , Hsiao-Wen Zan b , Yun-Chi Liang d 360 (PVP 360) polymer matrix cast by water solution. The solid-state photoluminescence quantum

300

Long-time electron spin storage via dynamical suppression of hyperfine-induced decoherence in a quantum dot  

SciTech Connect

The coherence time of an electron spin decohered by the nuclear spin environment in a quantum dot can be substantially increased by subjecting the electron to suitable dynamical decoupling sequences. We analyze the performance of high-level decoupling protocols by using a combination of analytical and exact numerical methods, and by paying special attention to the regimes of large interpulse delays and long-time dynamics, which are outside the reach of standard average Hamiltonian theory descriptions. We demonstrate that dynamical decoupling can remain efficient far beyond its formal domain of applicability, and find that a protocol exploiting concatenated design provides best performance for this system in the relevant parameter range. In situations where the initial electron state is known, protocols able to completely freeze decoherence at long times are constructed and characterized. The impact of system and control nonidealities is also assessed, including the effect of intrabath dipolar interaction, magnetic field bias and bath polarization, as well as systematic pulse imperfections. While small bias field and small bath polarization degrade the decoupling fidelity, enhanced performance and temporal modulation result from strong applied fields and high polarizations. Overall, we find that if the relative errors of the control pulse flip angles do not exceed 3%, decoupling protocols can still prolong the coherence time by up to 2 orders of magnitude.

Zhang, W.; Konstantinidis, N.; Dobrovitski, V.; Harmon, B.; Santos, L.; Viola, L.

2008-03-27T23:59:59.000Z

Note: This page contains sample records for the topic "quantum dot tracers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


301

Ultrafast Supercontinuum Spectroscopy of Carrier Multiplication and Biexcitonic Effects in Excited States of PbS Quantum Dots  

SciTech Connect

We examine the population dynamics of multiple excitons in PbS quantum dots using spectrally resolved ultrafast supercontinuum transient absorption (SC-TA) measurements. We simultaneously probe the first three excitonic transitions. The transient spectra show the presence of bleaching of absorption for the 1S{sub h}-1S{sub e} transition, as well as transients associated with the 1P{sub h}-1P{sub e} transition. We examine signatures of carrier multiplication (multiple excitons arising from a single absorbed photon) from analysis of the bleaching features in the limit of low absorbed photon numbers (

Sfeir M. Y.; Gesuele, F.; Koh, W.-K.; Murray, C.B.; Heinz, T.F.; Wong, C.W.

2012-06-01T23:59:59.000Z

302

The Structural Transition Behavior of CdSe/ZnS Core/shell Quantum Dots under High Pressure  

Science Conference Proceedings (OSTI)

The structural phase transition of CdSe/ZnS core/shell quantum dots (QDs) has been studied by in situ angle-dispersive X-ray diffraction under high pressure up to 53.6?GPa. The CdSe core transforms from wurtzite to rock-salt structure near 6.3?GPa and then to Cmcm or distorted Cmcm structure probably occurs at 45.1?GPa which has not been observed in CdSe nanomaterials before. The critical pressure from wurtzite to rock-salt and the bulk modulus of rock-salt phase are much higher than those for bulky and uncapped nanoparticle CdSe. The released sample can be kept in rock-salt phase for a certain time, verified by photoluminescence (PL) spectra, quite different from the reversible transition for pure CdSe. A reasonable interpretation of the experimental phenomena is given by comparing the bulk modulus of the core and shell and studying the stress sate of the core after decompression. Our study suggests that capping a hard shell is an effective approach to quench the high pressure phase of nanomaterial with a reversible phase transition.

Z Li; L Wang; B Liu; J Wang; B Liu; Q Li; B Zou; T Cui; Y Meng; H Mao

2011-12-31T23:59:59.000Z

303

CdSe/ZnS quantum dots based electrochemical immunoassay for the detection of phosphorylated bovine serum albumin  

SciTech Connect

A CdSe/ZnS quantum dot (QD) based electrochemical immunoassay of phosphorylated bovine serum albumin as a protein biomarker is presented. The QDs were used as labels and were conjugated with the secondary anti-phosphoserine antibody in a heterogeneous sandwich immunoassay. First, the primary BSA antibody was immobilized on polystyrene microwells, followed by the addition of BSA-OP. After that, the QD-labeled anti-phosphoserine antibody was added into microwells for immunorecognition. Finally, the bound QD was dissolved in an acid-dissolution step and was detected by electrochemical stripping analysis. The measured current responses were proportional to the concentration of BSA-OP. Under optimal conditions, the voltammetric response was linear over the range of 0.5 - 500 ng mL-1 of BSA-OP, with a detection limit of 0.5 ng mL-1 at a deposition potential of -1.2 V for 120 s. It also shows good reproducibility with a relative standard deviation of 8.6% of six times determination of 25 ng mL-1 of BSA-OP. This QD-based electrochemical immunoassay offers great promise for simple and cost-effective analysis of protein biomarkers.

Pinwattana, Kulwadee; Wang, Jun; Lin, Chiann Tso; Wu, Hong; Du, Dan; Lin, Yuehe; Chailapakul, Orawon

2010-11-15T23:59:59.000Z

304

Towards Applications of Quantum Dots: Surface Modification and Novel Electronic Properties  

SciTech Connect

The possibility of quantum confinement causing the intense visible luminescence seen in porous Si, first mentioned by Canham in 1991, led to enormous interest in that material. The large blue-shift in the band gap and increase in luminescent efficiency attributed to quantum confinement in porous Si, while still controversial, continues to fuel research on colloidal Si nanoparticles prepared by sonicating porous Si, and by solution chemistry. This interest continues, and has led naturally to an interest in colloidal Ge nanoparticles, since the elements are both indirect gap semiconductors, and the exciton of Ge has a larger Bohr radius. The earliest preparation of Ge nanoparticles by a colloidal chemistry method started as a continuation of the previous work on Si, but required either high temperatures and pressures, or laser annealing to produce crystalline nanoparticles. There has been only limited work on colloidal Ge nanoparticles prepared by sonicating porous Ge, with interest instead focused primarily on solution preparation of colloidal Ge nanoparticles. The reaction between Mg{sub 2}T and TCl{sub 4} in refluxing diglyme produced silicon and germanium nanoparticles in high yields, and the surface of these nanoparticles may be terminated using Grignard reagents. Since the particles produced by the initial metathesis reaction are from 2-10 nm in diameter, from 10-30% of their atoms are on the surface. With such a large proportion of atoms at the surface, its termination is vital to controlling their properties. Surface termination with Grignard reagents forms a robust protective layer at the surface of the nanoparticle, and provides an opportunity for further chemical manipulation. Though a considerable amount of work remains, chemically manipulating the surface of the nanoparticles may provide the ability to further tailor their properties and incorporate them into composite materials or devices. The ability to chemically change the surface of the nanoparticles yet retain the luminescence due to quantum confinement is unique to this preparative method.

Hope-Weeks, L; Foxx, G; Taylor, B

2003-04-18T23:59:59.000Z

305

Control of the direction and rate of nuclear spin flips in InAs quantum dots using detuned optical pulse trains  

E-Print Network (OSTI)

We find that detuning an optical pulse train from electronic transitions in quantum dots controls the direction of nuclear spin flips. The optical pulse train generates electron spins that precess about an applied magnetic field, with a spin component parallel to the field only for detuned pulses. This component leads to asymmetry in the nuclear spin flips, providing a way to produce a stable and precise value of the nuclear spin polarization. This effect is observed using two-color, time-resolved Faraday rotation and ellipticity.

S. G. Carter; A. Shabaev; Sophia E. Economou; T. A. Kennedy; A. S. Bracker; T. L. Reinecke

2009-01-16T23:59:59.000Z

306

Enhanced photocurrent gain and spectrum range based on the composite consisting of SnO{sub 2} nanowires and CdSe quantum dots  

Science Conference Proceedings (OSTI)

High sensitivity with additional spectral response based on the composite consisting of SnO{sub 2} nanowires (NWs) and CdSe quantum dots (QDs) has been demonstrated. The underlying mechanism is attributed to the spatial separation of photogenerated electrons and holes due to the charge transfer arising from type II band alignment between CdSe QD and SnO{sub 2} NW. This work shows that by selective decoration of suitable QDs, the photocurrent gain of NWs not only can be greatly enhanced, but also can be extended to a wider range photoresponse spectrum. Our result, therefore, provides a very useful guideline to create high efficiency photodetectors.

Lu, M. L.; Lin, C. H.; Chen, Y. F. [Department of Physics, National Taiwan University, Taipei 10617, Taiwan (China)

2011-08-22T23:59:59.000Z

307

Final Report for DE-FG36-08GO18007 "All-Inorganic, Efficient Photovoltaic Solid State Devices Utilizing Semiconducting Colloidal Nanocrystal Quantum Dots"  

SciTech Connect

We demonstrated robust colloidal quantum dot (QD) photovoltaics with high internal quantum efficiencies. In our structures, device durability is derived from use of all-inorganic atmospherically-stable semiconducting metal-oxide films together with QD photoreceptors. We have shown that both QD and metal-oxide semiconducting films and contacts are amenable to room temperature processing under minimal vacuum conditions, enabling large area processing of PV structures of high internal efficiency. We generated the state of the art devices with power conversion efficiency of more than 4%, and have shown that efficiencies as high as 9% are achievable in the near-term, and as high as 17% in the long-term.

Vladimir Bulovic and Moungi Bawendi

2011-09-30T23:59:59.000Z

308

Synthesis of cadmium telluride quantum wires and the similarity of their band gaps to those of equidiameter cadmium telluride quantum dots  

E-Print Network (OSTI)

ZnSe (ZB) ZnTe (ZB) CdS (W) CdSe (W) CdTe (ZB) AlN (W) GaN (experimental results from CdSe and InP dot-wire comparisons,0.66 ± 0.03) 13,15 and CdSe (A wire :A dot = 0.53 ± 0.05) 14

Sun, Jianwei

2008-01-01T23:59:59.000Z

309

Quantum Effect Materials: Methods of Fabrication of Quantum ... - TMS  

Science Conference Proceedings (OSTI)

Session A: Quantum Effect Materials: Methods of Fabrication of Quantum Dots. Session ... Nanometer size semiconductor crystallites show a striking evolution of  ...

310

Quantum Dots: Theory  

E-Print Network (OSTI)

SEPM) has been applied to CdSe [42], InP [43] and Si [42]calculated optical gap on CdSe nanocrystal size is presentedmass approach. In the case of CdSe ? = 1.18. The ? parameter

Vukmirovic, Nenad

2010-01-01T23:59:59.000Z

311

Nanotechnology for Solar-hydrogen Production via Photoelectrochemical Water-splitting: Design, Synthesis, Characterization, and Application of Nanomaterials and Quantum Dots  

E-Print Network (OSTI)

Hydrogen production by water-splitting using solar energy and nanostructure photocatalysts is very promising as a renewable, efficient, environmentally clean technology. The key is to reduce the cost of hydrogen production as well as increase the solar-to-hydrogen conversion efficiency by searching for cost-effective photocatalytic materials. In this dissertation, energy efficiency calculation was carried out based on hydrogen production observation to evaluate the nanomaterials activity. The results are important to gain better understanding of water-splitting reaction mechanism. Design, synthesis, characterization/properties and application of these nanomaterials was the road-map to achieve the research objectives. The design of TiO2 is selected based on unique photocatalytic and photovoltaic properties and high stability in aqueous solution. Various structures of nanocomposites TiO2 were designed according to their characteristics and potential activity. TiO2 with quantum dots, nanocomposites thin film, nanofibers, nanorods, nanowires (core/shell), nanotubes, nanopowders, nanoparticles, and nanosphere decorated with low cost metals, sensitized with dye, and doped with nitrogen are designed. Green physical and chemical synthesis methods such as sol-gel techniques, autoclave, microwave, electrospinning, wet impregnation, hydrothermal, chemical vapor deposition, template-based fabrication (porous anodic aluminium oxide membrane), drop casting, dip coating, wet coating were used to synthesize and fabricate the nanomaterials and quantum dots.Both bottom-up and top-down synthesis techniques were used. The ability to control and manipulate the size, shape/geometry, crystal structure, chemical compositions, interaction and interface properties of these materials at nano-scale during the synthesis enable to enhance their thermal, optical, chemical, electrical, …etc properties. Several characterization techniques such as XRD, XPS, EDS, SEM, UV-visible spectra, and optical microscopic and digital camera were also obtained to characterize the properties and confirm to achieve the desired design. The application or processing to test the activity of these nanomaterials for hydrogen production by water-splitting was conducted through extensive experimental program. It was carried out in a one photo-single column experimental set-up to detect hydrogen evolution. A high throughput screening process to evaluate single photo reduction catalysts was established here for simplicity, safety, cost-effective and flexibility of testing nanomaterials for water photoreduction reactivity and hydrogen generation. Therefore, methanol as electron donor or oxidation agent was mixed with water in equal volume ratio in order to prevent the oxygen evolution and only measured the time course of hydrogen production. The primary objectives of this study is to investigate the following (1) The structure-properties relationship through testing quantum dots, nanocomposites thin film, nanofibers, nanorods, nanowires (core/shell), nanotubes, nanopowders, nanoparticles, nanospheres of TiO2 decorated with metals, dye sensitization, and nitrogen-doping. (2) The role of adding electron donors/relays to solution and their effect on semiconductor surface-electrolyte interface under constant conditions such as KI, Mv 2, NaCl, NaHCO3, sea and pure water. (3) Band gap and defect engineering by cation and anion doping. (4) Quantum dots and dye sensitization effect. The nanomaterials activity evaluated based on observed hydrogen production rate (?mol/h/g) experimentally and based on the energy efficiency (percent) calculation. Major findings in this dissertation are (1) A high throughput screening process to evaluate single photoreduction catalysts for solar-hydrogen production by water-splitting was established. (2) nanofibers structure of TiO2 doped with

Alenzi, Naser D.

2010-12-01T23:59:59.000Z

312

Quantum Confined Structures  

Science Conference Proceedings (OSTI)

Sep 14, 2009 ... Classification of Energy Levels in Quantum Dot Structures by Means of Depleted Layer Spectroscopy Methods: Maria Kaniewska1; Olof ...

313

Self-pulsations and excitability in optically injected quantum-dot lasers: Impact of the excited states and spontaneous emission noise  

SciTech Connect

We study the dynamics of an optically injected quantum-dot laser accounting for excited states. Mapping of the bifurcations in the plane frequency detuning vs. injection strength shows that the relaxation rate scales the regions of locking and single- and double-period solutions, while the capture rate has a minor effect. Within the regions of time-periodic solutions, close to the saddle-node bifurcation boundary, we identify subregions where the output signal resembles excitable pulses as a result of the bottleneck phenomenon. We show that such emission is determined mainly by fluctuations in the occupation of the excited states. The interpulse time follows an inverse square root scaling law as a function of the detuning. In a deterministic system the pulses are periodic regardless of the detuning, but in the presence of noise, close to the locking region, the interpulse time follows a positively skewed normal distribution. For a fixed frequency detuning, increasing the noise strength can shift the mean of the interpulse time distribution and make the pulsations more periodic.

Olejniczak, Lukasz [Department of Applied Physics and Photonics, Brussels Photonics Team B-PHOT, Vrije Universiteit Brussel, 2 Pleinlaan, B-1050 Brussels (Belgium); SUPELEC, OPTEL, and LMOPS EA 4423 (Laboratoire Materiaux Optiques, Photonique et Systemes), 2 rue Edouard Belin, F-57070 Metz (France); Panajotov, Krassimir [Department of Applied Physics and Photonics, Brussels Photonics Team B-PHOT, Vrije Universiteit Brussel, 2 Pleinlaan, B-1050 Brussels (Belgium); Institute of Solid State Physics, 72 Tzarigradsko Chaussee Boulevard, 1784 Sofia (Bulgaria); Thienpont, Hugo [Department of Applied Physics and Photonics, Brussels Photonics Team B-PHOT, Vrije Universiteit Brussel, 2 Pleinlaan, B-1050 Brussels (Belgium); Sciamanna, Marc [SUPELEC, OPTEL, and LMOPS EA 4423 (Laboratoire Materiaux Optiques, Photonique et Systemes), 2 rue Edouard Belin, F-57070 Metz (France)

2010-08-15T23:59:59.000Z

314

Improving PbS Quantum Dot Solar Cell Power Conversion Efficiency to an NREL-Certified 4.4% (Fact Sheet)  

DOE Green Energy (OSTI)

Transition metal oxide improves overall efficiency and maintains performance with inexpensive metals. A research team at the National Renewable Energy Laboratory (NREL) has demonstrated that inserting a transition metal oxide (TMO) between the lead sulfide (PbS) quantum dot (QD) layer and the metal electrode eliminates the Schottky barrier that impedes efficient hole extraction and thereby improves the overall conversion efficiency. This allows for inexpensive metals such as Al to be employed without loss of performance. n-type TMOs consisting of molybdenum oxide (MoO{sub x}) and vanadium oxide (V{sub 2}O{sub x}) were used as an efficient hole extraction layer (HEL) in heterojunction ZnO/PbS QD solar cells. A 4.4% NREL-certified device was reported based on the MoO{sub x} HEL with Al as the back contact material, representing a more than 65% efficiency improvement compared with the case of Au contacting the PbS QD layer directly. The team finds the acting mechanism of the HEL to be a dipole formed at the MoO{sub x} and PbS interface, which enhances band bending to allow efficient hole extraction from the valence band of the PbS layer by MoO{sub x}. The carrier transport to the metal anode is likely enhanced through shallow gap states in the MoO{sub x} layer.

Not Available

2012-01-01T23:59:59.000Z

315

www.mdpi.com/journal/ijms Cytotoxic Effects of CdSe Quantum Dots on Maturation of Mouse Oocytes, Fertilization, and Fetal Development  

E-Print Network (OSTI)

Abstract: Quantum dots (QDs) are useful novel luminescent markers, but their embryonic toxicity is yet to be fully established, particularly in oocyte maturation and sperm fertilization. Earlier experiments by our group show that CdSe-core QDs have cytotoxic effects on mouse blastocysts and are associated with defects in subsequent development. Here, we further investigate the influence of CdSe-core QDs on oocyte maturation, fertilization, and subsequent pre- and postimplantation development. CdSe-core QDs induced a significant reduction in the rates of oocyte maturation, fertilization, and in vitro embryo development, but not ZnS-coated CdSe QDs. Treatment of oocytes with 500 nM CdSe-core QDs during in vitro maturation (IVM) led to increased resorption of postimplantation embryos and decreased placental and fetal weights. To our knowledge, this is the first study to report the negative impact of CdSe-core QDs on mouse oocyte development. Moreover, surface modification of CdSe-core QDs with ZnS effectively prevented this cytotoxicity.

Ming-shu Hsieh; Nion-heng Shiao; Wen-hsiung Chan

2009-01-01T23:59:59.000Z

316

Well-defined excited states of self-assembled InAs/InAlGaAs quantum dots on InP (001)  

SciTech Connect

Self-assembled InAs/InAlGaAs quantum dots (QDs) in an InAlGaAs matrix on InP (001) substrates were grown by the alternate growth method (AGQD), where an InAs layer with a thickness of 1 monolayer (ML) and an InAlGaAs layer with a thickness of 1 ML were alternately deposited. Cross-sectional transmission electron microscopy images indicated that the aspect ratio (height/width) for the AGQDs was {approx}0.25, which was higher than {approx}0.10 of conventionally grown InAs QDs. The photoluminescence (PL) peak position for the ground states of the AGQDs was 1.485 {mu}m with a linewidth broadening of 42 meV at room temperature, while the PL linewidth for the conventionally grown QDs was 85 meV. And the peaks for the excited-state transitions were also clearly observed from the excitation-power dependent PL. This is the first observation on the well-defined excited-state transitions from the InP-based InAs QDs, even though there were several reports on the features of the excited states.

Kim, Jin Soo; Lee, Jin Hong; Hong, Sung Ui; Kwack, Ho-Sang; Choi, Byung Seok; Oh, Dae Kon [Basic Research Laboratory, Electronics and Telecommunications Research Institute (ETRI), Daejeon (Korea, Republic of)

2005-08-01T23:59:59.000Z

317

Long-wavelength laser based on self-assembled InAs quantum dots in InAlGaAs on InP (001)  

SciTech Connect

Seven stacks of self-assembled InAs quantum dots (QDs) separated by 28 nm thick InAlGaAs barriers were grown on InP (001) substrate by a solid-source molecular-beam epitaxy and were investigated by cross-sectional transmission electron microscopy and photoluminescence spectroscopy. Gain guided broad-area lasers with a stripe width of 75 {mu}m were fabricated by using the seven-stacked InAs QD layers with the InAlGaAs-InAlAs material system on InP (001). The lasing operation from InAs QDs was observed up to 260 K and the characteristic temperature of the uncoated QD laser calculated from the temperature dependence of threshold current density was 377 K for temperatures up to 200 K, and 138 K above 200 K. The drastic decrease in the characteristic temperature above 200 K was mainly related to the thermal behavior of carriers in QDs, and possibly the thermal coupling of the QDs to the wetting layer and the waveguide region.

Kim, Jin Soo; Lee, Jin Hong; Hong, Sung Ui; Han, Won Seok; Kwack, Ho-Sang; Lee, Chul Wook; Oh, Dae Kon [Basic Research Laboratory, Electronics and Telecommunications Research Institute (ETRI), Daejeon (Korea, Republic of)

2004-08-09T23:59:59.000Z

318

Effect of proton bombardment on InAs dots and wetting layer in laser structures  

Science Conference Proceedings (OSTI)

The effect of proton bombardment on carrier lifetime and photoluminescence of InAs quantum dots was measured. Optical absorption and transmission electron microscopy show the dots retain their integrity under bombardment. A decrease in ground state photoluminescence with increasing dose is not explained by the decrease in dot carrier lifetime alone, but also by bombardment-induced non-radiative recombination in the wetting layer, which reduces the dot electron population at fixed excitation. To exploit the relative radiation immunity of quantum dots, it is necessary to maximise the dot density and capture probability per dot to minimize the effect of wetting layer recombination.

O'Driscoll, I.; Blood, P.; Smowton, P. M.; Sobiesierski, A. [School of Physics and Astronomy, Cardiff University, Queens Buildings, The Parade, Cardiff CF24 3AA (United Kingdom); Gwilliam, R. [Advanced Technology Institute, FEPS, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom)

2012-06-25T23:59:59.000Z

319

Thermodynamic Equilibrium-Driven Formation of Single-Sized Nanocrystals: Reaction Media Tuning CdSe Magic-Sized versus Regular Quantum Dots  

Science Conference Proceedings (OSTI)

A concept for the fundamental science of nanoparticle synthesis, thermodynamic equilibrium-driven formation of colloidal single-sized nanoparticle ensembles, is proposed and demonstrated in this manuscript, which addresses the controlled formation of CdSe magic-sized and regular quantum dots (MSQDs and RQDs). During formation, the former are magic-sized nuclei without further growth in size, while the latter experience nucleation and growth. Both MSQDs and RQDs exhibit bandgap emission, while the former have homogeneous spectra broadening only and the latter both homogeneous and inhomogeneous spectra broadening. The former are single-sized and the latter have size distribution. With continuous and homogeneous nucleation, the thermodynamically driven formation of MSQDs was realized via our one-pot noninjection approach, which features highly synthetic reproducibility and large-scale capability. With the proper tuning of the synthetic parameters, such as the nature of the reaction medium, that affect the thermodynamic equilibria, various CdSe MSQDs and RQDs were synthesized discriminately under otherwise identical synthetic formulation and reaction conditions; the reaction media were noncoordinating 1-octadecene, coordinating trioctylphosphine, and mixtures of the two. The nature of Cd precursors, affected also by the reaction media, plays a major role in the formation of MSQDs versus RQDs. The present investigation on the thermodynamically driven formation of CdSe single-sized nanoparticles via tuning of the reaction medium, mainly, brings novel insights into the formation mechanism and into the surface ligands of the resulting colloidal nanocrystals. More importantly, the present study provides novel experimental design and approaches to single-sized nanoparticles desired for various applications.

Yu, Kui [SIMS, NRC of Canada; Hu, Michael Z. [ORNL; Wang, Ruibing [SIMS, NRC of Canada; Le Piolet, Mickael [SIMS, NRC of Canada; Frotey, Marion [SIMS, NRC of Canada; Zaman, Md. Badruz [SIMS, NRC of Canada; Wu, Xiaohua [IMS, NRC of Canada; Leek, Donald M. [SIMS, NRC of Canada; Tao, Ye [IMS, NRC of Canada; Wilkinson, Diana [SIMS, NRC of Canada; Li, Chunsheng [National Research Council of Canada

2010-01-01T23:59:59.000Z

320

Structural, morphological, and magnetic characterization of In{sub 1-x}Mn{sub x}As quantum dots grown by molecular beam epitaxy  

SciTech Connect

In this paper, we present a method to order low temperature (LT) self-assembled ferromagnetic In{sub 1-x}Mn{sub x}As quantum dots (QDs) grown by molecular beam epitaxy (MBE). The ordered In{sub 1-x}Mn{sub x}As QDs were grown on top of a non-magnetic In{sub 0.4}Ga{sub 0.6}As/GaAs(100) QDs multi-layered structure. The modulation of the chemical potential, due to the stacking, provides a nucleation center for the LT In{sub 1-x}Mn{sub x}As QDs. For particular conditions, such as surface morphology and growth conditions, the In{sub 1-x}Mn{sub x}As QDs align along lines like chains. This work also reports the characterization of QDs grown on plain GaAs(100) substrates, as well as of the ordered structures, as function of Mn content and growth temperature. The substitutional Mn incorporation in the InAs lattice and the conditions for obtaining coherent and incoherent structures are discussed from comparison between Raman spectroscopy and x-ray analysis. Ferromagnetic behavior was observed for all structures at 2 K. We found that the magnetic moment axis changes from [110] in In{sub 1-x}Mn{sub x}As over GaAs to [1-10] for the ordered In{sub 1-x}Mn{sub x}As grown over GaAs template.

Ferri, F. A.; Marega, E. Jr. [Instituto de Fisica de Sao Carlos, Universidade de Sao Paulo, Sao Carlos 13560-970, SP (Brazil); Coelho, L. N. [Instituto de Fisica, Universidade de Brasilia, Brasilia 70919-970, DF (Brazil); Kunets, V. P.; Salamo, G. J. [Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701 (United States)

2012-08-01T23:59:59.000Z

Note: This page contains sample records for the topic "quantum dot tracers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
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321

Biological tracer method  

DOE Patents (OSTI)

The present invention is a biological tracer method for characterizing the movement of a material through a medium, comprising the steps of: introducing a biological tracer comprising a microorganism having ice nucleating activity into a medium; collecting at least one sample of the medium from a point removed from the introduction point; and analyzing the sample for the presence of the biological tracer. The present invention is also a method for using a biological tracer as a label for material identification by introducing a biological tracer having ice nucleating activity into a material, collecting a sample of a portion of the labelled material and analyzing the sample for the presence of the biological tracer. 2 figs.

Strong-Gunderson, J.M.; Palumbo, A.V.

1998-09-15T23:59:59.000Z

322

Biological tracer method  

DOE Patents (OSTI)

The present invention is a biological tracer method for characterizing the movement of a material through a medium, comprising the steps of: introducing a biological tracer comprising a microorganism having ice nucleating activity into a medium; collecting at least one sample of the medium from a point removed from the introduction point; and analyzing the sample for the presence of the biological tracer. The present invention is also a method for using a biological tracer as a label for material identification by introducing a biological tracer having ice nucleating activity into a material, collecting a sample of a portion of the labelled material and analyzing the sample for the presence of the biological tracer.

Strong-Gunderson, Janet M. (Ten Mile, TN); Palumbo, Anthony V. (Oak Ridge, TN)

1998-01-01T23:59:59.000Z

323

Thermally oxidized formation of new Ge dots over as-grown Ge dots in the Si capping layer  

Science Conference Proceedings (OSTI)

A Si-capped Ge quantum dot sample was self-assembly grown via Stranski-Krastanov mode in a molecular beam epitaxy system with the Si capping layer deposited at 300 deg. C. After annealing the sample in an oxygen atmosphere at 1000 deg. C, a structure, namely two layers of quantum dots, was formed with the newly formed Ge-rich quantum dots embedded in the oxidized matrix with the position accurately located upon the as-grown quantum dots. It has been found that the formation of such nanostructures strongly depends upon the growth temperature and oxygen atmosphere. A growth mechanism was proposed to explain the formation of the nanostructure based on the Ge diffusion from the as-grown quantum dots, Ge segregation from the growing oxide, and subsequent migration/agglomeration.

Nie Tianxiao [State Key Laboratory of Surface Physics, Fudan University, Shanghai 200433 (China); Materials Engineering, University of Queensland, Brisbane, Queensland QLD 4072 (Australia); Lin Jinhui; Shao Yuanmin; Wu Yueqin; Yang Xinju; Fan Yongliang; Jiang Zuimin [State Key Laboratory of Surface Physics, Fudan University, Shanghai 200433 (China); Chen Zhigang [Materials Engineering, University of Queensland, Brisbane, Queensland QLD 4072 (Australia); Zou Jin [Materials Engineering, University of Queensland, Brisbane, Queensland QLD 4072 (Australia); Centre for Microscopy and Microanalysis, University of Queensland, Brisbane, Queensland QLD 4072 (Australia)

2011-12-01T23:59:59.000Z

324

Assembly and Characterization of Nano-Complexes: Quantum ...  

Science Conference Proceedings (OSTI)

Assembly and Characterization of Nano-Complexes: Quantum Dot Encapsulated Liposomes. Idan Mandelbaum and Angela R. Hight Walker. ...

325

Dot Harris  

Energy.gov (U.S. Department of Energy (DOE))

Dot Harris was nominated by President Obama to be the Director of the Office of Economic Impact and Diversity at the United States Department of Energy. She was confirmed by the U.S. Senate on...

326

Dot Harris  

Energy.gov (U.S. Department of Energy (DOE))

LaDoris "Dot" Harris was nominated by President Obama to be the Director of the Office of Economic Impact and Diversity at the United States Department of Energy. She was confirmed by the...

327

Using Thermally Degrading, Partitioning and Nonreactive Tracers...  

Open Energy Info (EERE)

Type Topic 2 Tracers and Tracer Interpretation Project Description The goal of this project is to provide integrated tracer and tracer interpretation tools to facilitate this...

328

Accuracy of Circular Polarization as a Measure of Spin Polarization in Quantum Dot Qubits C. E. Pryor* and M. E. Flatte  

E-Print Network (OSTI)

dot spin light emitting diode provides a test of carrier spin injection into a qubit and a means. Towards this end, recent experiments [5] have dem- onstrated a spin light emitting diode (spin

Flatte, Michael E.

329

Quantum Effect Materials: Quantum Dots II - TMS  

Science Conference Proceedings (OSTI)

TMS Logo. About the 1996 Electronic Materials Conference: Friday Afternoon Sessions (June 28). June 26-28, 1996 · 38TH ELECTRONIC MATERIALS ...

330

Grazing Incidence Small-Angle X-Ray Scattering Studies of the Synthesis and Growth of CdS Quantum Dots from Constituent Atoms in SiO2 Matrix  

Science Conference Proceedings (OSTI)

Grazing incidence small angle X-ray scattering was applied to study the synthesis and growth of CdS quantum dots (QDs) from Cd and S atoms implanted in SiO{sub 2}. For a dose of 10{sup 17}/cm{sup 2}, the partial synthesis of CdS QDs occurred already during implantation, with only moderate size increase upon subsequent annealing up to T{sub a} = 1073 K. The dynamics of QD synthesis and growth were considerably different for just two times lower dose, where synthesis started only if the implanted samples were annealed at T{sub a} = 773 K or higher, with a strong increase of the size of QDs upon annealing at higher T{sub a}. The results suggest that high-dose implantation followed by low-temperature annealing could lead to better defined sizes and narrower size distributions of QDs.

Desnica, U. V. [R. Boskovic Institute, Zagreb, Croatia; Dubcek, P. [R. Boskovic Institute, Zagreb, Croatia; Desnica-Frankovic, I. D. [R. Boskovic Institute, Zagreb, Croatia; Buljan, M. [R. Boskovic Institute, Zagreb, Croatia; Bernstorff, S. [Sincrotrone Trieste, Basovizza, Italy; White, Clark W [ORNL

2003-01-01T23:59:59.000Z

331

Tracer Testing | Open Energy Information  

Open Energy Info (EERE)

Tracer Testing Tracer Testing Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Technique: Tracer Testing Details Activities (9) Areas (5) Regions (0) NEPA(0) Exploration Technique Information Exploration Group: Downhole Techniques Exploration Sub Group: Well Testing Techniques Parent Exploration Technique: Well Testing Techniques Information Provided by Technique Lithology: Stratigraphic/Structural: Fracture zones and formation permeability Hydrological: Flow rates, flow direction, hydrologic connections, storativity Thermal: Dictionary.png Tracer Testing: A method based on injecting chemical tracers into the reservoir and monitoring how long it takes and where those tracers travel. The purpose is to model subsurface hydrothermal flow characteristics.

332

Tracer Verification of Trajectory Models  

Science Conference Proceedings (OSTI)

Perfluorocarbon tracer data collected during the Cross Appalachian Tracer Experiment (CAPTEX '83) are used to determine the accuracy of three trajectory models: an isentropic, an isobaric, and a dimensional sigma model. The root-mean-square ...

Philip L. Haagenson; Ying-Hwa Kuo; Marina Syumanich; Nelson L. Seaman

1987-03-01T23:59:59.000Z

333

Obtaining Velocities from Tracer Distributions  

Science Conference Proceedings (OSTI)

A simple advective-diffusive system with uniform, horizontal flow in a channel and fixed boundary concentrations of two tracers is analyzed for the tracer concentrations in the interior. The deduced concentrations are then treated as given ...

Manuel E. Fiadeiro; George Veronis

1984-11-01T23:59:59.000Z

334

Tracers and Tracer Testing: Design, Implementation, Tracer Selection, and Interpretation Methods  

SciTech Connect

Conducting a successful tracer test requires adhering to a set of steps. The steps include identifying appropriate and achievable test goals, identifying tracers with the appropriate properties, and implementing the test as designed. When these steps are taken correctly, a host of tracer test analysis methods are available to the practitioner. This report discusses the individual steps required for a successful tracer test and presents methods for analysis. The report is an overview of tracer technology; the Suggested Reading section offers references to the specifics of test design and interpretation.

G. Michael Shook; Shannon L.; Allan Wylie

2004-01-01T23:59:59.000Z

335

Tracer Diffusion Databases for ICME  

Science Conference Proceedings (OSTI)

... of a large repository of stable isotopes that can be utilized for tracer diffusion .... Lattice Dynamics and Thermodynamics of Lithium Battery Materials LiMPO4 ...

336

BNL | Tracer Technology Group | BNL  

NLE Websites -- All DOE Office Websites (Extended Search)

Tracer Technology Group Tracer Technology Group Tracer Technology Image The Tracer Technology Group (TTG) developed the use of perfluorocarbon tracers (PFTs) as tools for studying long range atmospheric transport and dispersion in the early 1980s.We are world leaders in the use of PFTs for solving diverse research and engineering problems in the atmospheric sciences, the energy production and utility industries, and building characterization. The unique capabilities of the TTG are derived from our analytical expertise, infrastructure, and experience. We have developed PFT analytical methods that have detection limits at the femtogram level. We can measure global background levels of PFTS at the parts per quadrillion levels. Our scientists and technical staff have extensive experience in

337

Definition: Tracer Testing | Open Energy Information  

Open Energy Info (EERE)

Jump to: navigation, search Dictionary.png Tracer Testing A method based on injecting chemical tracers into the reservoir and monitoring how long it takes and where those tracers...

338

Tracer dating and ocean ventilation  

E-Print Network (OSTI)

The interpretation of transient tracer observations depends on dif•cult to obtain information on the evolution in time of the tracer boundary conditions and interior distributions. Recent studies have attempted to circumvent this problem by making use of a derived quantity, age, based on the simultaneous distribution of two complementary tracers, such as tritium and its daughter, helium 3. The age is defined with reference to the surface such that the boundary condition takes on a constant value of zero. We use a two-dimensional model to explore the circumstances under which such a combination of conservation equations for two complementary tracers can lead to a cancellation of the time derivative terms. An interesting aspect of this approach is that mixing can serve as a source or sink of tracer based age. We define an idealized "ventilation age tracer " that is conservative with respect to mixing, and we explore how its behavior compares with that of the tracer-based ages over a range of advective and diffusive parameters. 1.

G. Thiele; J. L. Sarmiento

1990-01-01T23:59:59.000Z

339

Tracer airflow measurement system (TRAMS)  

DOE Patents (OSTI)

A method and apparatus for measuring fluid flow in a duct is disclosed. The invention uses a novel high velocity tracer injector system, an optional insertable folding mixing fan for homogenizing the tracer within the duct bulk fluid flow, and a perforated hose sampling system. A preferred embodiment uses CO.sub.2 as a tracer gas for measuring air flow in commercial and/or residential ducts. In extant commercial buildings, ducts not readily accessible by hanging ceilings may be drilled with readily plugged small diameter holes to allow for injection, optional mixing where desired using a novel insertable foldable mixing fan, and sampling hose.

Wang, Duo (Albany, CA)

2007-04-24T23:59:59.000Z

340

Gas tracer composition and method  

SciTech Connect

The invention provides a method for tagging methane by adding thereto one or more of the tracer compounds sulfur hexafluoride and chloropentafluoroethane. The methane being tagged is normally being stored in underground storage fields to provide identity and proof of ownership of the gas. The two tracer compounds are readily detectable at very low concentrations by electron capture gas chromatography apparatus which can be made portable and thus suitable for use in the field.

Malcosky, N. D.; Koziar, G.

1985-11-05T23:59:59.000Z

Note: This page contains sample records for the topic "quantum dot tracers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

A Tracer Test Using Ethanol as a Two-Phase Tracer and 2-Naphthalene  

Open Energy Info (EERE)

Tracer Test Using Ethanol as a Two-Phase Tracer and 2-Naphthalene Tracer Test Using Ethanol as a Two-Phase Tracer and 2-Naphthalene Sulfonate as a Liquid-Phase Tracer at the Coso Geothermal Field Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Conference Proceedings: A Tracer Test Using Ethanol as a Two-Phase Tracer and 2-Naphthalene Sulfonate as a Liquid-Phase Tracer at the Coso Geothermal Field Details Activities (1) Areas (1) Regions (0) Abstract: A tracer test was conducted at the Coso geothermal field in order to characterize the flow patterns of fluid injected into well 68-20RD. A conservative liquid phase tracer, 2-naphthalene sulfonate, and a two-phase tracer, ethanol, were injected into well 68-20RD. Surrounding production wells were sampled over the subsequent 125 days and analyzed for the two tracers. The liquid-phase tracer showed negligible returns, whereas the

342

Bright three-band white light generated from CdSe/ZnSe quantum dot-assisted Sr{sub 3}SiO{sub 5}:Ce{sup 3+},Li{sup +}-based white light-emitting diode with high color rendering index  

SciTech Connect

In this study, bright three-band white light was generated from the CdSe/ZnSe quantum dot (QD)-assisted Sr{sub 3}SiO{sub 5}:Ce{sup 3+},Li{sup +}-based white light-emitting diode (WLED). The CdSe/ZnSe core/shell structure was confirmed by energy dispersive x-ray spectroscopy and x-ray photoelectron spectroscopy. The CdSe/ZnSe QDs showed high quantum efficiency (79%) and contributed to the high luminous efficiency ({eta}{sub L}) of the fabricated WLED. The WLED showed bright natural white with excellent color rendering property ({eta}{sub L}=26.8 lm/W, color temperature=6140 K, and color rendering index=85) and high stability against the increase in forward bias currents from 20 to 70 mA.

Jang, Ho Seong; Kwon, Byoung-Hwa; Jeon, Duk Young [Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, 373-1, Guseong-dong, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Yang, Heesun [Department of Materials Science and Engineering, Hongik University, 72-1, Sangsu-dong, Mapo-gu, Seoul 121-791 (Korea, Republic of)

2009-10-19T23:59:59.000Z

343

A Tracer Test Using Ethanol as a Two-Phase Tracer and 2-Naphthalene...  

Open Energy Info (EERE)

Tracer Test Using Ethanol as a Two-Phase Tracer and 2-Naphthalene Sulfonate as a Liquid-Phase Tracer at the Coso Geothermal Field Jump to: navigation, search GEOTHERMAL...

344

Photonic implementation for the topological cluster-state quantum computer  

SciTech Connect

An implementation of the topological cluster-state quantum computer is suggested, in which the basic elements are linear optics, measurements, and a two-dimensional array of quantum dots. This overcomes the need for nonlinear devices to create a lattice of entangled photons. Whereas the thresholds found for computational errors are quite satisfactory (above 10{sup -3}), the estimates of the minimum efficiencies needed for the detectors and quantum dots are beyond current technology's reach. This is because we rely heavily on probabilistic entangling gates, which introduces loss into the scheme irrespective of detector and quantum-dot efficiencies.

Herrera-Marti, David A.; Jennings, David; Rudolph, Terry [Institute for Mathematical Sciences, Imperial College London, London SW7 2BW (United Kingdom); Fowler, Austin G. [Centre for Quantum Computer Technology, University of Melbourne, Victoria (Australia)

2010-09-15T23:59:59.000Z

345

(AlIn)GaN Multi Quantum Wells for Blue Lasers by ...  

Science Conference Proceedings (OSTI)

... 13th International Conference on Defects--Recognition, Imaging and Physics in ... Capacitance Spectroscopy of Deep States in Quantum Dot Heterostructures.

346

Gas Bubbles as Oceanographic Tracers  

Science Conference Proceedings (OSTI)

Air bubbles can be used as oceanographic tracers that indicate the strength of a downwelling current by which they are subducted. In a tidal front in the Fraser Estuary, British Columbia, Canada, vertical currents of up to 0.70 m s?1 subduct ...

Burkard Baschek; David M. Farmer

2010-01-01T23:59:59.000Z

347

A hypercube Ray-tracer  

Science Conference Proceedings (OSTI)

We describe a hypercube ray-tracing program for rendering computer graphics. For small models, which fit in the memory of a single processor, the ray-tracer uses a scattered decomposition of pixels to balance the load, and achieves a very high efficiency. ...

J. Salmon; J. Goldsmith

1989-01-01T23:59:59.000Z

348

DOT | OpenEI  

Open Energy Info (EERE)

50 50 Varnish cache server Browse Upload data GDR 429 Throttled (bot load) Error 429 Throttled (bot load) Throttled (bot load) Guru Meditation: XID: 2142257150 Varnish cache server DOT Dataset Summary Description The data included in this submission is United States Department of Transportation (DOT) data on rates and revenue statistics up to 1995. The data includes state motor-fuel tax receipts, 1919-1995, state motor fuel taxes and related receipts, 1950-1995, and state and federal motor fuel tax rates, 1919-1995 The data is presented in .xlsx format. Source DOT Date Released Unknown Date Updated Unknown Keywords DOT highway motor vehicles rates revenues Data application/vnd.openxmlformats-officedocument.spreadsheetml.sheet icon State motor-fuel tax receipts, 1919-1995 (xlsx, 13.8 KiB)

349

OpenEI - DOT  

Open Energy Info (EERE)

http:en.openei.orgdatasetstaxonomyterm1980 en DOT rate and revenues summary to 1995 http:en.openei.orgdatasetsnode148

The data included in this submission is United...

350

Tracer dispersion in the turbulent convective layer  

Science Conference Proceedings (OSTI)

Experimental results for passive tracer dispersion in the turbulent surface layer under convective conditions are presented. In this case, the dispersion of tracer particles is determined by the interplay of two mechanisms: buoyancy and advection. ...

Alex Skvortsov; Milan Jamriska; Timothy C. DuBois

351

Meteorological Tracer Techniques for Parameterizing Atmospheric Dispersion  

Science Conference Proceedings (OSTI)

Although tracer materials have been used in atmospheric dispersion studies for decades, basic information about meteorological tracer techniques is scattered among a number of different sources. This paper attempts to pull together this ...

Warren B. Johnson

1983-05-01T23:59:59.000Z

352

Propagation of Tracer Signals in Boundary Currents  

Science Conference Proceedings (OSTI)

The propagation of a range of tracer signals in a simple model of the deep western boundary current is examined. Analytical expressions are derived in certain limits for the transit-time distributions and the propagation times (tracer ages) of ...

Darryn W. Waugh; Timothy M. Hall

2005-09-01T23:59:59.000Z

353

Can Paleoceanographic Tracers Constrain Meridional Circulation Rates?  

Science Conference Proceedings (OSTI)

The ability of paleoceanographic tracers to constrain rates of transport is examined using an inverse method to combine idealized observations with a geostrophic model. Considered are the spatial distribution, accuracy, and types of tracers ...

Peter Huybers; Geoffrey Gebbie; Olivier Marchal

2007-02-01T23:59:59.000Z

354

New Quantum Dot Transistor Counts Individual Photons  

Science Conference Proceedings (OSTI)

... (See table for a comparison of various types of single ... Photons enter the device and their energy is transferred to ... a record high for this type of photon ...

2012-06-05T23:59:59.000Z

355

Graphene Drumheads Tuned to Make Quantum Dots  

Science Conference Proceedings (OSTI)

... Able to conduct electricity with little resistance at room temperature, graphene is a prime candidate for applications ranging from flexible displays to ...

2013-07-08T23:59:59.000Z

356

Peptide coated quantum dots for biological applications  

E-Print Network (OSTI)

X-ray photoelectron spectroscopy of CdSe nanocrystals withof nearly monodis- perse CdSe/CdS core/shell nanocrystalsstrongly luminescing Zns-capped CdSe nanocrystals,” J. Phys.

2006-01-01T23:59:59.000Z

357

First principle thousand atom quantum dot calculations  

E-Print Network (OSTI)

and A. Zunger, Appl. Phys. Lett. system bulk_CdSe (100)_CdSe (lll).CdSe (110)_CdSe (110)_GaAs Ap AE (meV) g (llO)-Si

Wang, Lin-Wang; Li, Jingbo

2004-01-01T23:59:59.000Z

358

Hierarchically Assembled Quantum Dot Sensitized Photovoltaics  

Science Conference Proceedings (OSTI)

[1] Furthermore, CO2 emissions due to fossil fuel consumption keep rising and threaten to permanently affect the environment in a  ...

359

Multiple-tracer gas analyzer  

SciTech Connect

A multi-gas tracer system has been designed, built, and used on an explosively fractured oil shale rubble bed. This paper deals exclusively with the hardware, software, and overall operation of the tracer system. This system is a field portable, self-contained unit, which utilizes a mass spectrometer for gas analysis. The unit has a 20 channel sample port capability and is controlled by a desk top computer. The system is configured to provide a dynamic sensitivity range of up to six orders of magnitude. A roots blower is manifolded to the unit to provide continuous flow in all sample lines. The continuous flow process allows representative samples as well as decreasing the time between each measurement. Typical multiplex cycle time to evaluate four unique gases is approximately 12 seconds.

Uhl, J.E.

1982-01-01T23:59:59.000Z

360

dot5301.PDF  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Transportation Transportation Office of the Secretary of Transportation SUBJECT: Department of Transportation Programs, Policies, and Procedures Affecting American Indians, Alaska Natives, and Tribes ORDER DOT 5301.1 1. PURPOSE. To ensure that programs, policies, and procedures administered by the Department of Transportation (DOT) are responsive to the needs and concerns of American Indians, Alaska Natives, and tribes. 2. REFERENCES. This list is not all-inclusive but is intended to help in the understanding of this DOT Order. a. Executive Orders and Memoranda: (1) Executive Order 12866, Regulatory Planning and Review (58 Federal Register 51739, October 4, 1993), dated September 30, 1993. (2) Executive Order 12875, Enhancing the Intergovernmental Partnership (58 Federal Register 58093, October 28, 1993), dated October 26, 1993.

Note: This page contains sample records for the topic "quantum dot tracers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

On Quantum Coherence Effects in Photo and Solar Cells  

E-Print Network (OSTI)

We show that quantum coherence can increase the quantum efficiency of various thermodynamic systems. For example, we can enhance the quantum efficiency for a quantum dot photocell, a laser based solar cell and the photo-Carnot quantum heat engine. Our results are fully consistent with the laws of thermodynamics contrary to comments found in the paper of A.P. Kirk, Phys. Rev. Lett. 106, 048703 (2011).

Kimberly Chapin; Konstantin Dorfman; Anatoly Svidzinsky; Marlan Scully

2010-12-23T23:59:59.000Z

362

Photonic Technologies for Quantum Information Processing  

E-Print Network (OSTI)

The last several years have seen tremendous progress toward practical optical quantum information processing, including the development of single- and entangled-photon sources and high-efficiency photon counting detectors, covering a range of wavelengths. We review some of the recent progress in the development of these photonic technologies. KEY WORDS: Quantum dot; entanglement; down-conversion; single-photon detector.

Prem Kumar; Paul Kwiat; Alan Migdall; Sae Woo Nam; Jelena Vuckovic; Franco N. C. Wong

2004-01-01T23:59:59.000Z

363

Petroleum characterization by perfluorocarbon tracers  

SciTech Connect

Perfluorocarbon tracers (PFTs), a class of six compounds, were used to help characterize the Shallow Oil Zone (SOZ) reservoir at the Naval Petroleum Reserve in California (NPRC) at Elk Hills. The SOZ reservoir is undergoing a pilot gas injection program to assess the technical feasibility and economic viability of injecting gas into the SOZ for improved oil recovery. PFTs were utilized in the pilot gas injection to qualitatively assess the extent of the pilot gas injection so as to determine the degree of gas containment within the SOZ reservoir.

Senum, G.I.; Fajer, R.W. (Brookhaven National Lab., Upton, NY (United States)); Harris, B.R. Jr. (USDOE Naval Petroleum Reserves in California, Tupman, CA (United States)); DeRose, W.E. (Bechtel Petroleum Operations, Inc., Tupman, CA (United States)); Ottaviani, W.L. (Chevron U.S.A., Inc., Bakersfield, CA (United States))

1992-02-01T23:59:59.000Z

364

Quantum Computation Quantum Information  

E-Print Network (OSTI)

Quantum Computation and Quantum Information Samuel J. Lomonaco, Jr. and Howard E. Brandt editors Searches with a Quantum Robot .............................................. 12 pages Benioff, Paul Perturbation Theory and Numerical Modeling Quantum Logic Operations with a Large of Qubits

Lomonaco Jr., Samuel J.

365

Doublet Tracer Testing in Klamath Falls, Oregon  

DOE Green Energy (OSTI)

A tracer test was carried out in a geothermal doublet system to study the injection behavior of a developed reservoir known to be fractured. The doublet produces about 320 gpm of 160 F water that is used for space heating and then injected; the wells are spaced 250 ft apart. Tracer breakthrough was observed in 2 hours and 45 minutes in the production well, indicating fracture flow. However, the tracer concentrations were low and indicated porous media flow; the tracers mixed with a reservoir volume much larger than a fracture.

Gudmundsson, J.S.; Johnson, S.E.; Horne, R.N.; Jackson, P.B.; Culver, G.G.

1983-12-15T23:59:59.000Z

366

Session BB: Quantum Effect Materials: Quantum Dots I - TMS  

Science Conference Proceedings (OSTI)

The structure of InP was observed by atomic force microscope(AFM) and transmission electron microscope(TEM). InP was grown two-dimensionally at least to ...

367

Quantum Teleportation from a Propagating Photon to a Solid-State Spin Qubit  

E-Print Network (OSTI)

The realization of a quantum interface between a propagating photon used for transmission of quantum information, and a stationary qubit used for storage and manipulation, has long been an outstanding goal in quantum information science. A method for implementing such an interface between dissimilar qubits is quantum teleportation, which has attracted considerable interest not only as a versatile quantum-state-transfer method but also as a quantum computational primitive. Here, we experimentally demonstrate transfer of quantum information carried by a photonic qubit to a quantum dot spin qubit using quantum teleportation. In our experiment, a single photon in a superposition state of two colors -- a photonic qubit is generated using selective resonant excitation of a neutral quantum dot. We achieve an unprecedented degree of indistinguishability of single photons from different quantum dots by using local electric and magnetic field control. To teleport a photonic qubit, we generate an entangled spin-photon state in a second quantum dot located 5 meters away from the first and interfere the photons from the two dots in a Hong-Ou-Mandel set-up. A coincidence detection at the output of the interferometer heralds successful teleportation, which we verify by measuring the resulting spin state after its coherence time is prolonged by an optical spin-echo pulse sequence. The demonstration of successful inter-conversion of photonic and semiconductor spin qubits constitute a major step towards the realization of on-chip quantum networks based on semiconductor nano-structures.

Wei-bo Gao; P. Fallahi; E. Togan; A. Delteil; Y. S. Chin; J. Miguel-Sanchez; A. Imamoglu

2013-07-03T23:59:59.000Z

368

Microseismic Tracer Particles for Hydraulic Fracturing  

NLE Websites -- All DOE Office Websites (Extended Search)

Microseismic Tracer Particles for Hydraulic Fracturing Microseismic Tracer Particles for Hydraulic Fracturing Microseismic Tracer Particles for Hydraulic Fracturing Scientists at Los Alamos National Laboratory have developed a method by which microseismic events can be discriminated/detected that correspond to only the portion of the hydraulic fracture that contains the proppant material and can be expected to be conductive to the flow of oil and gas. July 3, 2013 Microseismic Tracer Particles for Hydraulic Fracturing Figure 1: A graph of ionic conductivity as a function of temperature for the anti-perovskite Li3OCl. Available for thumbnail of Feynman Center (505) 665-9090 Email Microseismic Tracer Particles for Hydraulic Fracturing Applications: Oil and gas production Geophysical exploration Benefits: Tracks the disposition of material in a hydraulic fracturing

369

Microsoft PowerPoint - Tracer plume detection-LANL(Fessenden...  

NLE Websites -- All DOE Office Websites (Extended Search)

Artificially introduced or naturally present All tracers will partition into liquid and gas phases -T,P, Depth Dependent Information Gathered from Tracers (1)Reservoir volume...

370

Experiments to Evaluate and Implement Passive Tracer Gas Methods...  

NLE Websites -- All DOE Office Websites (Extended Search)

Experiments to Evaluate and Implement Passive Tracer Gas Methods to Measure Ventilation Rates in Homes Title Experiments to Evaluate and Implement Passive Tracer Gas Methods to...

371

Dot-Bombs: lessons from the dot-com debacle  

Science Conference Proceedings (OSTI)

While a great deal can be learned from examining dot-com successes, even more can be learned from studying dot-com failures. The number of failures, unfortunately, is in the many hundreds and has resulted in the loss of billions of dollars and thousands ... Keywords: e-commerce models, e-commerce success, internet commerce

Nakato Hirakubo; Hershey H. Friedman

2002-09-01T23:59:59.000Z

372

Experimental Determination of Tracer Dispersivity in Fractures  

DOE Green Energy (OSTI)

Reinjection of waste hot water is commonly practiced in most geothermal fields, primarily as a means of disposal. Surface discharge of these waste waters is usually unacceptable due to the resulting thermal and chemical pollution. Although reinjection can help to main reservoir pressure and fluid volume, in some cases a decrease in reservoir productivity has been observed. This is caused by rapid flow of the reinjected water through fractures connecting the injector and producers. As a result, the water is not sufficiently heated by the reservoir rock, and a reduction in enthalpy of the produced fluids is seen. Tracer tests have proven to be valuable to reservoir engineers for the design of a successful reinjection program. By injecting a slug of tracer and studying the discharge of surrounding producing wells, an understanding of the fracture network within a reservoir can be provided. In order to quantify the results of a tracer test, a model that accurately describes the mechanisms of tracer transport is necessary. One such mechanism, dispersion, is like a smearing out of a tracer concentration due to the velocity gradients over the cross section of flow. If a dispersion coefficient can be determined from tracer test data, the fracture width can be estimated. The purpose of this project was to design and construct an apparatus to study the dispersion of a chemical tracer in flow through a fracture.

Gilardi, J.; Horns, R.N.

1985-01-22T23:59:59.000Z

373

Tracer Developments: Results of Experimental Studies  

DOE Green Energy (OSTI)

Tracers can be used to monitor the movement of groundwaters and geothermal fluids and they can be used as a reference to quantify changes in fluid chemistry as a result of injection. Despite their potential importance to the geothermal operator, very few tracers are presently available and of those that are, little is known about their stability or behavior at the elevated temperatures that typify resources capable of electric power generation. During the past two years the University of Utah Research Institute has been involved in tracer research and testing, largely through the DOE Injection Research Program. The purpose of this paper is to summarize the results of these laboratory and field investigations.

Adams, M.C.; Ahn, J.H.; Bentley, H.; Moore, J.N.; Veggeberg, S.

1986-01-21T23:59:59.000Z

374

Quantum Money  

Science Conference Proceedings (OSTI)

Quantum Money. Purpose: ... I will present a concrete quantum money scheme based on quantum superpositions of diagrams that encode knots. ...

2011-10-25T23:59:59.000Z

375

Tracer Leakage from Modeled Agulhas Rings  

Science Conference Proceedings (OSTI)

In a numerical, isopycnal, ocean model the mixing is investigated with the environment of two idealized Agulhas rings, one that splits, and one that remains coherent. The evolution of a passive tracer, initially contained within the rings, shows ...

L. de Steur; P. J. van Leeuwen; S. S. Drijfhout

2004-06-01T23:59:59.000Z

376

Tracers and Potential Vorticities in Ocean Dynamics  

Science Conference Proceedings (OSTI)

The Ertel potential vorticity theorem for stratified viscous fluids in a rotating system is analyzed herein. A set of “tracers,” that is, materially conserved scalar quantities, and the corresponding Ertel potential vorticities are used to obtain ...

Michael V. Kurgansky; Giorgio Budillon; Ettore Salusti

2002-12-01T23:59:59.000Z

377

Determining Velocities and Mixing Coefficients from Tracers  

Science Conference Proceedings (OSTI)

The effort to determine oceanic velocities from tracer distributions relies on a knowledge of the effects of mixing. However, the macroscopic diffusion coefficient, K, is generally not known and must be calculated along with the velocity. The ...

Jae Hak Lee; George Veronis

1989-04-01T23:59:59.000Z

378

When Are Eddy Tracer Fluxes Directed Downgradient?  

Science Conference Proceedings (OSTI)

The mechanisms controlling the direction of eddy tracer fluxes are examined using eddy-resolving isopycnic experiments for a cyclic zonal channel. Eddy fluxes are directed downgradient on average when either (i) there is a Lagrangian increase in ...

Chris Wilson; Richard G. Williams

2006-02-01T23:59:59.000Z

379

Using Biofuel Tracers to Study Alternative Combustion Regimes  

E-Print Network (OSTI)

Section B (NIMB) Using Biofuel Tracers to Study Alternativeinjection. We investigate biofuel HCCI combustion, and use

Mack, John Hunter; Flowers, Daniel L.; Buchholz, Bruce A.; Dibble, Robert W.

2006-01-01T23:59:59.000Z

380

Analysis of tracer and thermal transients during reinjection  

DOE Green Energy (OSTI)

This work studied tracer and thermal transients during reinjection in geothermal reserviors and developed a new technique which combines the results from interwell tracer tests and thermal injection-backflow tests to estimate the thermal breakthrough times. Tracer tests are essential to determine the degree of connectivity between the injection wells and the producing wells. To analyze the tracer return profiles quantitatively, we employed three mathematical models namely, the convection-dispersion (CD) model, matrix diffusion (MD) model, and the Avodnin (AD) model, which were developed to study tracer and heat transport in a single vertical fracture. We considered three types of tracer tests namely, interwell tracer tests without recirculation, interwell tracer tests with recirculation, and injection-backflow tracer tests. To estimate the model parameters, we used a nonlinear regression program to match tracer return profiles to the solutions.

Kocabas, I.

1989-10-01T23:59:59.000Z

Note: This page contains sample records for the topic "quantum dot tracers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

Fermilab | Take Five for Goal Zero | Gloves | PVC Dotted Gloves  

NLE Websites -- All DOE Office Websites (Extended Search)

PVC Dotted Gloves PVC Dotted Gloves Description Color Finish Uses FNAL Stock Number PVC dot coating on both sides for grip and abrasion resistance 5050 cottonacrylic launders...

382

Theory and simulation of quantum photovoltaic devices based on the non-equilibrium Green's function formalism  

Science Conference Proceedings (OSTI)

This article reviews the application of the non-equilibrium Green's function formalism to the simulation of novel photovoltaic devices utilizing quantum confinement effects in low dimensional absorber structures. It covers well-known aspects of the fundamental ... Keywords: NEGF, Photovoltaics, Quantum dot, Quantum well

U. Aeberhard

2011-12-01T23:59:59.000Z

383

Thermal Stability of Chelated Indium Activable Tracers  

SciTech Connect

The thermal stability of indium tracer chelated with organic ligands ethylenediaminetetraacetic acid (EDTA) and nitrilotriacetic acid (NTA) was measured for reservoir temperatures of 150, 200, and 240 C. Measurements of the soluble indium concentration was made as a function of time by neutron activation analysis. From the data, approximate thermal decomposition rates were estimated. At 150 C, both chelated tracers were stable over the experimental period of 20 days. At 200 C, the InEDTA concentration remained constant for 16 days, after which the thermal decomposition occurred at a measured rate constant of k = 0.09 d{sup -1}. The thermal decomposition of InNTA at 200 C showed a first order reaction with a measured rate constant of k = 0.16 d{sup -1}. At 240 C, both indium chelated tracers showed rapid decomposition with rate constants greater than 1.8 d{sup -1}. The data indicate that for geothermal reservoir with temperatures up to about 200 C, indium chelated tracers can be used effectively for transit times of at least 20 days. These experiments were run without reservoir rock media, and do not account for concomitant loss of indium tracer by adsorption processes.

Chrysikopoulos, Costas; Kruger, Paul

1986-01-21T23:59:59.000Z

384

Enhanced Oil Recovery: Aqueous Flow Tracer Measurement  

SciTech Connect

A low detection limit analytical method was developed to measure a suite of benzoic acid and fluorinated benzoic acid compounds intended for use as tracers for enhanced oil recovery operations. Although the new high performance liquid chromatography separation successfully measured the tracers in an aqueous matrix at low part per billion levels, the low detection limits could not be achieved in oil field water due to interference problems with the hydrocarbon-saturated water using the system's UV detector. Commercial instrument vendors were contacted in an effort to determine if mass spectrometry could be used as an alternate detection technique. The results of their work demonstrate that low part per billion analysis of the tracer compounds in oil field water could be achieved using ultra performance liquid chromatography mass spectrometry.

Joseph Rovani; John Schabron

2009-02-01T23:59:59.000Z

385

Geologic flow characterization using tracer techniques  

DOE Green Energy (OSTI)

A new tracer flow-test system has been developed for in situ characterization of geologic formations. This report describes two sets of test equipment: one portable and one for testing in deep formations. Equations are derived for in situ detector calibration, raw data reduction, and flow logging. Data analysis techniques are presented for computing porosity and permeability in unconfined isotropic media, and porosity, permeability and fracture characteristics in media with confined or unconfined two-dimensional flow. The effects of tracer pulse spreading due to divergence, dispersion, and porous formations are also included.

Klett, R. D.; Tyner, C. E.; Hertel, Jr., E. S.

1981-04-01T23:59:59.000Z

386

A 3-D hydrodynamic dispersion model for modeling tracer transport in Geothermal Reservoirs  

E-Print Network (OSTI)

diffusion of a tracer or a radionuclide. This new module ofsimulate processes of tracer/radionuclide transport using ana) a tracer or a radionuclide is present and transported

Wu, Yu-Shu; Pruess, Karsten

1998-01-01T23:59:59.000Z

387

Fabrication and characterization of quantum-confined optoelectronic devices based on CdSe nanocrystals  

E-Print Network (OSTI)

Colloidal semiconductor quantum dots (QDs), or nanocrystals (NCs), are the subject of intense research for their novel size dependent optical and electronic properties. Since the development of synthetic methods to produce ...

Woo, Wing-Keung, 1972-

2002-01-01T23:59:59.000Z

388

Effects of stacking faults on the electronic structures of quantum rods  

E-Print Network (OSTI)

nanorod, stacking fault, CdSe, empirical pseudopotentialstructure quantum dots, like CdSe and InP. The stackingabout 1 meV/atom in CdSe [7]), and it depends sensitively on

Wang, Lin-Wang

2004-01-01T23:59:59.000Z

389

Quantum groups  

Science Conference Proceedings (OSTI)

The theory of Quantum groups, although rather young, since the expression Quantum ... introduction of a suitable form of the quantum group, the algebra A ...

390

Tracer Test Interpretation Methods for Reservior Properties  

DOE Green Energy (OSTI)

The purpose of this project is to develop tools that can be used to interpret tracer tests and obtain estimates of reservoir and operational parameters. These tools (mostly in the form of spreadsheet applications) can be used to optimize geothermal resource management.

Shook, George Michael

2001-08-01T23:59:59.000Z

391

Eulerian Simulation of Tracer Distribution during CAPTEX  

Science Conference Proceedings (OSTI)

We compared observed and model-simulated surface concentration on a spatial wale of 1100 km and a temporal scale of 36 h. The Eulerian tracer model calculated advection by the mean winds and gradient transport for subgrid-scale turbulent ...

Richard A. Brost; Philip L. Haagenson; Ying-Hwa Kuo

1988-05-01T23:59:59.000Z

392

Tracer Testing At Coso Geothermal Area (2006) | Open Energy Information  

Open Energy Info (EERE)

Tracer Testing At Coso Geothermal Area (2006) Tracer Testing At Coso Geothermal Area (2006) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Tracer Testing At Coso Geothermal Area (2006) Exploration Activity Details Location Coso Geothermal Area Exploration Technique Tracer Testing Activity Date 2006 Usefulness useful DOE-funding Unknown Exploration Basis To characterize the flow patterns of fluid injected into well 68-20RD. Notes A conservative liquid phase tracer, 2-naphthalene sulfonate, and a two-phase tracer, ethanol, were injected into well 68-20RD. Surrounding production wells were sampled over the subsequent 125 days and analyzed for the two tracers. The results demonstrate the efficacy of the simultaneous use of liquid-phase and two-phase tracers in fluid-depleted geothermal

393

A Method of Evaluating Atmospheric Models Using Tracer Measurements  

Science Conference Proceedings (OSTI)

The authors have developed a method that uses tracer measurements as the basis for comparing and evaluating wind fields. An important advantage of the method is that the wind fields are evaluated from the tracer measurements without introducing ...

Darko Kora?in; James Frye; Vlad Isakov

2000-02-01T23:59:59.000Z

394

Constraining North Atlantic circulation with transient tracer observations  

E-Print Network (OSTI)

The capability of transient tracers to constrain the ocean circulation in the North Atlantic is explored. Study of an idealized tracer shows that inferences of circulation properties from transient state distributions are ...

Li, Xingwen, 1968-

2003-01-01T23:59:59.000Z

395

A Continuous Fast-Response Dual-Tracer Analyzer for Halogenated Atmospheric Tracer Studies  

Science Conference Proceedings (OSTI)

An apparatus for the simultaneous measurement of two tracers, sulfur hexafluoride (SF6) and a perfluorocarbon compound, is introduced. The new instrument is a modification of a commercially available fast-response, continuous analyzer for single ...

James P. Rydock; Brian K. Lamb

1994-10-01T23:59:59.000Z

396

Quantum Cryptography and Quantum Computation  

E-Print Network (OSTI)

Quantum Cryptography and Quantum Computation Network Security Course Project Report by Hidayath.2 Bases of the Hilbert space . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.3 Quantum principle . . . . . . . . . . . . . . . . . . . . . . 5 3 Quantum Cryptography 6 3.1 The BB84 protocol

North Carolina at Chapel Hill, University of

397

Transforming quantum operations: quantum supermaps  

E-Print Network (OSTI)

We introduce the concept of quantum supermap, describing the most general transformation that maps an input quantum operation into an output quantum operation. Since quantum operations include as special cases quantum states, effects, and measurements, quantum supermaps describe all possible transformations between elementary quantum objects (quantum systems as well as quantum devices). After giving the axiomatic definition of supermap, we prove a realization theorem, which shows that any supermap can be physically implemented as a simple quantum circuit. Applications to quantum programming, cloning, discrimination, estimation, information-disturbance trade-off, and tomography of channels are outlined.

G. Chiribella; G. M. D'Ariano; P. Perinotti

2008-04-01T23:59:59.000Z

398

Tracer Testing at Dixie Valley, Nevada, Using Pyrene Tetrasulfonate Amino  

Open Energy Info (EERE)

Tracer Testing at Dixie Valley, Nevada, Using Pyrene Tetrasulfonate Amino Tracer Testing at Dixie Valley, Nevada, Using Pyrene Tetrasulfonate Amino G, and Fluorescein Jump to: navigation, search OpenEI Reference LibraryAdd to library Journal Article: Tracer Testing at Dixie Valley, Nevada, Using Pyrene Tetrasulfonate Amino G, and Fluorescein Abstract A series of four tracer tests was recently conducted at the Dixie Valley, Nevada, geothermal reservoir in order to determine fluid-flow processes and to evaluate candidate tracers for use in hydrothermal systems. These tests have resulted in the first successful use of the compounds amino G and pyrenetetrasulfonate as tracers in a geothermal reservoir. The tracer candidates were subjected to simulated hydrothermal conditions in laboratory reactors at temperatures as high as 300°C in order to determine

399

Passive Tracer Gas Methods to Measure  

NLE Websites -- All DOE Office Websites (Extended Search)

Experiments to Evaluate and Implement Experiments to Evaluate and Implement Passive Tracer Gas Methods to Measure Ventilation Rates in Homes Melissa Lunden, David Faulkner, Elizabeth Heredia, Sebastian Cohn, Darryl Dickerhoff, Federico Noris, Jennifer Logue, Toshifumi Hotchi, Brett Singer and Max H. Sherman Environmental Energy Technologies Division October 2012 LBNL-5984E 2 Disclaimer: This document was prepared as an account of work sponsored by the United States

400

Quantum Tetrahedra  

E-Print Network (OSTI)

We discuss in details the role of Wigner 6j symbol as the basic building block unifying such different fields as state sum models for quantum geometry, topological quantum field theory, statistical lattice models and quantum computing. The apparent twofold nature of the 6j symbol displayed in quantum field theory and quantum computing -a quantum tetrahedron and a computational gate- is shown to merge together in a unified quantum-computational SU(2)-state sum framework.

Mauro Carfora; Annalisa Marzuoli; Mario Rasetti

2010-01-25T23:59:59.000Z

Note: This page contains sample records for the topic "quantum dot tracers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

Measurements of Spin Dynamics Reveal that Shape of Excitons in Quantum Rod Heterostructures Changes with Size (Fact Sheet)  

Science Conference Proceedings (OSTI)

Using femtosecond cross-polarized transient grating (CPTG) and polarization anisotropy, NREL was able to probe the extent of electronic delocalization in CdSe/CdS quantum rod heterostructures (QRH) with a 'dot-in-rod' geometry.

Not Available

2012-06-01T23:59:59.000Z

402

Quantum entanglement for acoustic spintronics  

SciTech Connect

We consider the entanglement of spins for two electrons contributing to the acoustoelectric current driven by a surface acoustic wave (SAW) in two adjacent narrow channels by calculating their exchange energy (J). The channels belong to an acoustic nanocircuit which comprises a network of quasi-one-dimensional pinched-off channels serving as wires along which SAW quantum dots transport electrons. This is motivated by possible practical applications involving quantum information processing and quantum computers. We calculate J as a function of time as the electrons travel side-by-side in the adjacent channels and as a function of the distance between the centers of the channels. The leakage from the state in which the system is prepared, is calculated. The oscillations in the leakage indicate the probability for the electron system to make transitions between the ground and excited states, or for an electron to hop back and forth between channels.

Gumbs, Godfrey; Abranyos, Yonatan [Department of Physics and Astronomy, Hunter College of the City University of New York, 695 Park Avenue, New York, New York 10021 (United States)

2004-11-01T23:59:59.000Z

403

Women @ Energy: Dot Harris | Department of Energy  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Dot Harris Dot Harris Women @ Energy: Dot Harris March 15, 2013 - 1:06pm Addthis LaDoris (Dot) Harris is the Director of the Office of Economic Impact and Diversity. LaDoris (Dot) Harris is the Director of the Office of Economic Impact and Diversity. LaDoris (Dot) Harris is the Director of the Office of Economic Impact and Diversity. She was nominated by President Obama and confirmed by the U.S. Senate on March 29, 2012. She has served at some of the world's largest firms including General Electric, ABB Service, and Westinghouse Electric Company. Ms. Harris leads the Department's efforts to ensure minorities and historically underrepresented communities participate fully in Departmental programs. Ms. Harris oversees funding for minority institutions, advocates for small business contracting opportunities, and

404

Optical resonators and quantum dots: and excursion into quantum optics, quantum information and photonics.  

E-Print Network (OSTI)

??Modern communications technology has encouraged an intimate connection between Semiconductor Physics and Optics, and this connection shows best in the combination of electron-confining structures with… (more)

Bianucci, Pablo, 1975-

2008-01-01T23:59:59.000Z

405

Hydrogeology of the Blautopf spring - Tracer tests in Blauhohle cave |  

Open Energy Info (EERE)

Hydrogeology of the Blautopf spring - Tracer tests in Blauhohle cave Hydrogeology of the Blautopf spring - Tracer tests in Blauhohle cave Jump to: navigation, search OpenEI Reference LibraryAdd to library Web Site: Hydrogeology of the Blautopf spring - Tracer tests in Blauhohle cave Author Andreas Kucha Published Publisher Not Provided, 2012 DOI Not Provided Check for DOI availability: http://crossref.org Online Internet link for Hydrogeology of the Blautopf spring - Tracer tests in Blauhohle cave Citation Andreas Kucha. Hydrogeology of the Blautopf spring - Tracer tests in Blauhohle cave [Internet]. 2012. [cited 2013/10/17]. Available from: http://www.agw.kit.edu/english/blauhoele_cave.php Retrieved from "http://en.openei.org/w/index.php?title=Hydrogeology_of_the_Blautopf_spring_-_Tracer_tests_in_Blauhohle_cave&oldid=688895"

406

Tracer Testing At Coso Geothermal Area (1993) | Open Energy Information  

Open Energy Info (EERE)

Tracer Testing At Coso Geothermal Area (1993) Tracer Testing At Coso Geothermal Area (1993) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Tracer Testing At Coso Geothermal Area (1993) Exploration Activity Details Location Coso Geothermal Area Exploration Technique Tracer Testing Activity Date 1993 Usefulness useful DOE-funding Unknown Exploration Basis To determine the steam and water mass flow rate Notes The method involves precisely metered injection of liquid and vapor phase tracers into the two-phase production pipeline and concurrent sampling of each phase downstream of the injection point. Subsequent chemical analysis of the steam and water samples for tracer content enables the calculation of mass flowrate for each phase given the known mass injection rates of

407

Tracer populations in the local group  

E-Print Network (OSTI)

, in good agreement with previous work. I go on to develop a set of tracer mass estimators that build on previous work which make use of actual (and not projected) distance and proper motion data, reflecting the amount and quality of data now available to us... ages range from 1-10 Gyr; the scale height of the population increases with age from 200 kpc to around 700 kpc and the metallicity decreases with age to around 20% solar. The typical content of this disk population are A stars, planetary nebulae...

Watkins, Laura Louise

2011-04-19T23:59:59.000Z

408

Measurements of waste tank passive ventilation rates using tracer gases  

Science Conference Proceedings (OSTI)

This report presents the results of ventilation rate studies of eight passively ventilated high-level radioactive waste tanks using tracer gases. Head space ventilation rates were determined for Tanks A-101, AX-102, AX-103, BY-105, C-107, S-102, U-103, and U-105 using sulfur hexafluoride (SF{sub 6}) and/or helium (He) as tracer gases. Passive ventilation rates are needed for the resolution of several key safety issues. These safety issues are associated with the rates of flammable gas production and ventilation, the rates at which organic salt-nitrate salt mixtures dry out, and the estimation of organic solvent waste surface areas. This tracer gas study involves injecting a tracer gas into the tank headspace and measuring its concentration at different times to establish the rate at which the tracer is removed by ventilation. Tracer gas injection and sample collection were performed by SGN Eurisys Service Corporation and/or Lockheed Martin Hanford Corporation, Characterization Project Operations. Headspace samples were analyzed for He and SF{sub 6} by Pacific Northwest National Laboratory (PNNL). The tracer gas method was first demonstrated on Tank S-102. Tests were conducted on Tank S-102 to verify that the tracer gas was uniformly distributed throughout the tank headspace before baseline samples were collected, and that mixing was sufficiently vigorous to maintain an approximately uniform distribution of tracer gas in the headspace during the course of the study. Headspace samples, collected from a location about 4 in away from the injection point and 15, 30, and 60 minutes after the injection of He and SF{sub 6}, indicated that both tracer gases were rapidly mixed. The samples were found to have the same concentration of tracer gases after 1 hour as after 24 hours, suggesting that mixing of the tracer gas was essentially complete within 1 hour.

Huckaby, J.L.; Olsen, K.B.; Sklarew, D.S.; Evans, J.C.; Remund, K.M.

1997-09-01T23:59:59.000Z

409

Preferred methods of analysis for chemical tracers in moderate...  

Open Energy Info (EERE)

Preferred methods of analysis for chemical tracers in moderate- and high-temperature geothermal environments Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Report:...

410

Tracer Testing At Raft River Geothermal Area (1984) | Open Energy...  

Open Energy Info (EERE)

L.; Yorgason, K. R.; Moore, J. N. (1 December 1984) Preferred methods of analysis for chemical tracers in moderate- and high-temperature geothermal environments Retrieved from...

411

Tracer Testing At East Mesa Geothermal Area (1984) | Open Energy...  

Open Energy Info (EERE)

L.; Yorgason, K. R.; Moore, J. N. (1 December 1984) Preferred methods of analysis for chemical tracers in moderate- and high-temperature geothermal environments Retrieved from...

412

Advancing Reactive Tracer Methods for Measuring Thermal Evolution...  

Open Energy Info (EERE)

History Facebook icon Twitter icon Advancing Reactive Tracer Methods for Measuring Thermal Evolution in CO2- and Water-Based Geothermal Reservoirs Geothermal Lab Call Project...

413

Hydrogeology of the Blautopf spring - Tracer tests in Blauhohle...  

Open Energy Info (EERE)

2012 DOI Not Provided Check for DOI availability: http:crossref.org Online Internet link for Hydrogeology of the Blautopf spring - Tracer tests in Blauhohle cave...

414

TRACER DETECTION TECHNOLOGY CORP. PRODUCTS AND SERVICES FOR CORPORATE...  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

TRACER DETECTION TECHNOLOGY CORP. PRODUCTS AND SERVICES FOR CORPORATE AND GOVERNMENT SECURITY 3463 MAGIC DRIVE, SUITE T-19 SAN ANTONIO, TX 78229 March 29, 2009 Office of the...

415

Development of a Set of Inherent Particulate and Gas Tracers...  

NLE Websites -- All DOE Office Websites (Extended Search)

of results to the number and quality of tracer elements and if new (interfering) sources are detected. * Determine primary and secondary PM 2.5 contributions from power...

416

High photo-excited carrier multiplication by charged InAs dots in AlAs/GaAs/AlAs resonant tunneling diode  

E-Print Network (OSTI)

We present an approach for the highly sensitive photon detection based on the quantum dots (QDs) operating at temperature of 77K. The detection structure is based on an AlAs/GaAs/AlAs double barrier resonant tunneling diode combined with a layer of self-assembled InAs QDs (QD-RTD). A photon rate of 115 photons per second had induced 10nA photocurrent in this structure, corresponding to the photo-excited carrier multiplication factor of 10^7. This high multiplication factor is achieved by the quantum dot induced memory effect and the resonant tunneling tuning effect of QD-RTD structure.

Wang, Wangping; Xiong, Dayuan; Li, Ning; Lu, Wei

2007-01-01T23:59:59.000Z

417

High photo-excited carrier multiplication by charged InAs dots in AlAs/GaAs/AlAs resonant tunneling diode  

E-Print Network (OSTI)

We present an approach for the highly sensitive photon detection based on the quantum dots (QDs) operating at temperature of 77K. The detection structure is based on an AlAs/GaAs/AlAs double barrier resonant tunneling diode combined with a layer of self-assembled InAs QDs (QD-RTD). A photon rate of 115 photons per second had induced 10nA photocurrent in this structure, corresponding to the photo-excited carrier multiplication factor of 10^7. This high multiplication factor is achieved by the quantum dot induced memory effect and the resonant tunneling tuning effect of QD-RTD structure.

Wangping Wang; Ying Hou; Dayuan Xiong; Ning Li; Wei Lu

2007-10-15T23:59:59.000Z

418

Quantum discord  

NLE Websites -- All DOE Office Websites (Extended Search)

Quantum discord Quantum discord 1663 Los Alamos science and technology magazine Latest Issue:November 2013 All Issues » submit Quantum discord A distinguishing aspect of quantum mechanics discovered at Los Alamos that may be critical to building a quantum computer March 25, 2013 Spinning coins turning into binary numbers Quantum computing Quantum computing can be carried out without the delicate entanglement of qubits previously believed to be necessary Quantum computing, in which quantum bits of information (or qubits) juggle a "superposition" of multiple values simultaneously, offers to unleash tremendous computational power if the qubits can be effectively isolated to prevent decoherence: information describing quantum states dispersing into the environment. But recent research has shown that quantum computing can be carried out

419

Quantum Institute  

NLE Websites -- All DOE Office Websites (Extended Search)

Quantum Institute Quantum Institute Quantum Institute A new research frontier awaits! Our door is open and we thrive on mutually beneficial partnerships, collaborations that drive innovations and new technologies. Contact Leader Malcolm Boshier (505) 665-8892 Email Two of LANL's most successful quantum technology initiatives: quantum cryptography and the race for quantum computer The area of quantum information, science, and technology is rapidly evolving, with important applications in the areas of quantum cryptography, quantum computing, quantum metrology, and advanced quantum-based sensors, some of which are directly relevant to the Laboratory's national security mission. Mission Foster a vigorous intellectual environment at LANL Define and develop strategic thrusts Target and pursue funding opportunities

420

A quantum logic gate between a solid-state quantum bit and a photon  

E-Print Network (OSTI)

Integrated quantum photonics provides a promising route towards scalable solid-state implementations of quantum networks, quantum computers, and ultra-low power opto-electronic devices. A key component for many of these applications is the photonic quantum logic gate, where the quantum state of a solid-state quantum bit (qubit) conditionally controls the state of a photonic qubit. These gates are crucial for development of robust quantum networks, non-destructive quantum measurements, and strong photon-photon interactions. Here we experimentally realize a quantum logic gate between an optical photon and a solid-state qubit. The qubit is composed of a quantum dot (QD) strongly coupled to a nano-cavity, which acts as a coherently controllable qubit system that conditionally flips the polarization of a photon on picosecond timescales, implementing a controlled-NOT (cNOT) gate. Our results represent an important step towards solid-state quantum networks and provide a versatile approach for probing QD-photon inter...

Kim, Hyochul; Shen, Thomas C; Solomon, Glenn S; Waks, Edo; 10.1038/nphoton.2013.48

2013-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "quantum dot tracers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

Effective quantum dynamics of interacting systems with inhomogeneous coupling  

SciTech Connect

We study the quantum dynamics of a single mode (particle) interacting inhomogeneously with a large number of particles and introduce an effective approach to find the accessible Hilbert space, where the dynamics takes place. Two relevant examples are given: the inhomogeneous Tavis-Cummings model (e.g., N atomic qubits coupled to a single cavity mode, or to a motional mode in trapped ions) and the inhomogeneous coupling of an electron spin to N nuclear spins in a quantum dot.

Lopez, C. E.; Retamal, J. C. [Departamento de Fisica, Universidad de Santiago de Chile, Casilla 307 Correo 2, Santiago (Chile); Christ, H. [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching (Germany); Solano, E. [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching (Germany); Physics Department, ASC, and CeNS, Ludwig-Maximilians-Universitaet, Theresienstrasse 37, 80333 Munich (Germany); Departamento de Ciencias, Seccion Fisica, Pontificia Universidad Catolica del Peru, Apartado 1761, Lima (Peru)

2007-03-15T23:59:59.000Z

422

DOTS: support for effective video surveillance  

Science Conference Proceedings (OSTI)

DOTS (Dynamic Object Tracking System) is an indoor, real-time, multi-camera surveillance system, deployed in a real office setting. DOTS combines video analysis and user interface components to enable security personnel to effectively monitor views of ... Keywords: multiple video streams, person tracking, security cameras, video surveillance

Andreas Girgensohn; Don Kimber; Jim Vaughan; Tao Yang; Frank Shipman; Thea Turner; Eleanor Rieffel; Lynn Wilcox; Francine Chen; Tony Dunnigan

2007-09-01T23:59:59.000Z

423

Tracer Testing At East Mesa Geothermal Area (1983) | Open Energy  

Open Energy Info (EERE)

Tracer Testing At East Mesa Geothermal Area (1983) Tracer Testing At East Mesa Geothermal Area (1983) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Tracer Testing At East Mesa Geothermal Area (1983) Exploration Activity Details Location East Mesa Geothermal Area Exploration Technique Tracer Testing Activity Date 1983 Usefulness not indicated DOE-funding Unknown Notes Two field experiments were conducted to develop chemical tracer procedures for use with injection-backflow testing, one on the fracture-permeability Raft River reservoir and the other on the matrix-permeability East Mesa reservoir. Results from tests conducted with incremental increases in the injection volume at both East Mesa and Raft River suggests that, for both reservoirs, permeability remained uniform with increasing distance from the

424

National Biomedical Tracer Facility. Project definition study  

Science Conference Proceedings (OSTI)

We request a $25 million government-guaranteed, interest-free loan to be repaid over a 30-year period for construction and initial operations of a cyclotron-based National Biomedical Tracer Facility (NBTF) in North Central Texas. The NBTF will be co-located with a linear accelerator-based commercial radioisotope production facility, funded by the private sector at approximately $28 million. In addition, research radioisotope production by the NBTF will be coordinated through an association with an existing U.S. nuclear reactor center that will produce research and commercial radioisotopes through neutron reactions. The combined facilities will provide the full range of technology for radioisotope production and research: fast neutrons, thermal neutrons, and particle beams (H{sup -}, H{sup +}, and D{sup +}). The proposed NBTF facility includes an 80 MeV, 1 mA H{sup -} cyclotron that will produce proton-induced (neutron deficient) research isotopes.

Schafer, R.

1995-02-14T23:59:59.000Z

425

Dynamic Properties of Quantum Dot Distributed Feedback Lasers  

E-Print Network (OSTI)

. Whittington, Z. Zou, L. Olona, C. Wuggins, T. Tumolillo, J. Zilko, and P. M. Varangis, CLEO/PHAST, 2004

New Mexico, University of

426

Optoelectronic and photonic control of single quantum dots  

E-Print Network (OSTI)

r/a = 0.3 and normalised slab height d/a = 0.7. There is a photonic band gap stretching from ?/a ? 3.2 to ?/a ? 4.2, with a single resonant mode confined inside it. The field distributions of the TE-like mode are shown, which is known as the dipole...

Dewhurst, Samuel James

2010-10-12T23:59:59.000Z

427

Hybrid Quantum Dots in InAs Inauguraldissertation  

E-Print Network (OSTI)

Ivelin A. Mollov*, Peter S. Boyadzhiev**, Atanas D. Donev** University of Plovdiv "Paisii Hilendarski; to supplement, compare #12;Ivelin A. Mollov, Peter S. Boyadzhiev, Atanas D. Donev 116 and analyze the data & BATSCHWAROV (1972) #12;Ivelin A. Mollov, Peter S. Boyadzhiev, Atanas D. Donev 120 Table 3. Summary

Amrhein, Valentin

428

Temperature-Dependent Electron Transport in Quantum Dot Photovoltaics  

E-Print Network (OSTI)

the market grows, the price of PV continue to fall as seenprice reduction, there exist several methods to bring down the cost-per-Watt for PV.

Padilla, Derek

2013-01-01T23:59:59.000Z

429

Coherence and Spin in GaAs Quantum Dots  

E-Print Network (OSTI)

. The eletrical proper- ties of our thin films on the 101ÂŻ0 substrate are comparable with those of a single

Heller, Eric

430

Temperature-Dependent Electron Transport in Quantum Dot Photovoltaics  

E-Print Network (OSTI)

intensity of incoming solar flux ? sun . This is the basisE)dE E g where ? sun is the incident solar radiation flux.sun Figure 4.1: Schematic representation of path of incident sunlight for three solar

Padilla, Derek

2013-01-01T23:59:59.000Z

431

Nanoscale engineering boosts performance of quantum dot light...  

NLE Websites -- All DOE Office Websites (Extended Search)

provide many advantages over standard lighting technologies, such as incandescent bulbs, especially in the areas of efficiency, operating lifetime and the color quality of...

432

K3: Advanced Display Applications of Quantum Dot Light Emitting ...  

Science Conference Proceedings (OSTI)

Synthesis of Monolithic Iron Incorporated Silica Aerogels by Ambient Pressure Drying · Synthesis of Ultrahigh-density Sub 10 nm Co Nanowires Arrays by the ...

433

Temperature-Dependent Electron Transport in Quantum Dot Photovoltaics  

E-Print Network (OSTI)

photocell for converting solar radiation into electricalthe atmosphere the solar radiation passes through to reach? sun is the incident solar radiation flux. For the SQL, the

Padilla, Derek

2013-01-01T23:59:59.000Z

434

V7, Quantum Dot Light Emitting Devices and Exciton Recombination ...  

Science Conference Proceedings (OSTI)

DD3, A New Approach to Make ZnO-Cu2O Heterojunctions for Solar Cells ... E2, AlGaAs/GaAs/GaN Wafer Fused HBTs with Ar Implanted Extrinsic Collectors.

435

Effect of Material Strain on Embedded Quantum Dot Fluorescence ...  

Science Conference Proceedings (OSTI)

Approaching Multimaterial 3D Nanostructured Gas Phase Nanoxerographic Printers · Carbon Nanotube Coatings Laser Power and Energy Measurements.

436

Classification of Energy Levels in Quantum Dot Structures by Means ...  

Science Conference Proceedings (OSTI)

About this Abstract. Meeting, 13th International Conference on Defects-- Recognition, Imaging and Physics in Semiconductors. Symposium, 13th International ...

437

Electrical Characterization of the Lead Sulfide Quantum Dots Using ...  

Science Conference Proceedings (OSTI)

About this Abstract. Meeting, Materials Science & Technology 2013. Symposium, Synthesis and Structural and Functional Characterization of Thin Films and ...

438

Supramolecular quantum dot-porphyrin assemblies for biological oxygen sensing  

E-Print Network (OSTI)

Generating metabolic profiles of tumors provides a spatiotemporal map of the concentration of key species to assess and quantify tumor growth, metabolism, and response to therapy. Because the tumor microenvironment is ...

Lemon, Christopher M. (Christopher Michael)

2013-01-01T23:59:59.000Z

439

Unraveling the mystery of quantum-dot blinking  

NLE Websites -- All DOE Office Websites (Extended Search)

genetic stress reactions in cells Counting small RNA in disease-causing organisms DREAM tool increases space weather predictions Questions about how plants die leads to climate...

440

Commercialization of Quantum Dot White Light Emitting Diode technology  

E-Print Network (OSTI)

It is well known that the use of high-brightness LEDs for illumination has the potential to substitute conventional lighting and revolutionize the lighting industry over the next 10 to 20 years. However, successful penetration ...

Zhao, Xinyue, M. Eng. Massachusetts Institute of Technology

2006-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "quantum dot tracers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


441

Pulsed Single-Photon Resonant Cavity Quantum Dot LED  

Science Conference Proceedings (OSTI)

Previously, the authors demonstrated single-photon emission of cw-operated InP QDs up to at least 80 K in a simple light emitting diode (LED) configuration [2].

442

Temperature-Dependent Electron Transport in Quantum Dot Photovoltaics  

E-Print Network (OSTI)

a 150 nm layer of 10 mol. % tin oxide in indium oxide (indium tin oxide, or ITO). The pattern allows for six 1 mmof transparent conducting oxides: indium tin oxide (ITO) and

Padilla, Derek

2013-01-01T23:59:59.000Z

443

Single quantum dot (QD) imaging of fluid flow near surfaces  

Science Conference Proceedings (OSTI)

water-soluble (CdSe)ZnS QDs with a core size of 6 nm within a region of order 100 nm of a surface . Results are presented for the two in-plane components of ...

444

Quantum Dots-based Reverse Phase Protein Microarray  

E-Print Network (OSTI)

Qdots, with two STV per Qdot. CdSe/ZnS Qdots are embedded inf_chen@lbl.gov Abstract CdSe nanocrystals, also calledmaterials made of a CdSe core of a few nanometers, and

Shingyoji, Masato; Gerion, Daniele; Pinkel, Dan; Gray, Joe W.; Chen, Fanqing

2005-01-01T23:59:59.000Z

445

Electronic transport in CdSe quantum dot arrays  

E-Print Network (OSTI)

When an isolated piece of conductor is sufficiently small, the energy to add another electron can be larger than the available thermal energy, and the number of electrons on the island is well-defined. If the island is ...

Morgan, Nicole Yen-i, 1971-

2001-01-01T23:59:59.000Z

446

Cavity Enhancement of Single Quantum Dot Emission in the Blue  

E-Print Network (OSTI)

in the blue and green spectral region by changing the alloy content. The access to this wavelength range may prove particularly useful for free-space cryptography. It also corresponds to the range where the commercially avail- able ultrafast single... . Christmann, D. Simeonov, R. Butte´, E. Feltin, J.-F. Carlin, N. Grandjean, Appl. Phy. Lett. 89, 261101 (2006) 4. F. Semond, I.R. Sellers, F. Natali, D. Byrne, M. Leroux, J. Massies, N. Ollier, J. Leymarie, P. Disseix, A. Vasson, Appl. Phys. Lett. 87, 021102...

2009-12-27T23:59:59.000Z

447

Temperature-Dependent Electron Transport in Quantum Dot Photovoltaics  

E-Print Network (OSTI)

4.3 (a) The AM1.5G solar spectrum matched with a black bodythe properties of the solar spectrum is discussed, leading4.3: (a) The AM1.5G solar spectrum matched with a black body

Padilla, Derek

2013-01-01T23:59:59.000Z

448

Reengineering the Optics of Quantum Dots with Mechanical ...  

Science Conference Proceedings (OSTI)

... nanomechanical energy harvesting ... s s - atomistic tight-binding theory: spin-orbit interaction, no piezo ... minimal piezoelectric effect (ignore) ...

2009-11-05T23:59:59.000Z

449

Quantum Dot Based Cell Motility, Invasion, and Metastasis Assays  

Carolyn Larabell, Paul Alivisatos, and colleagues have discovered a powerful tool for studying cell motility and migration ...

450

Temperature-Dependent Electron Transport in Quantum Dot Photovoltaics  

E-Print Network (OSTI)

6, the ITO back contact, the RTD temperature sensor, and theresistive temperature detector (RTD) is a calibrated piecethe sample temperature. The RTD is necessary as the ITC 503

Padilla, Derek

2013-01-01T23:59:59.000Z

451

Analysis of Passive Tracer Transport as Modeled by an Atmospheric General Circulation Model  

Science Conference Proceedings (OSTI)

Tracers without feedback on the atmosphere are used to probe tropospheric transport. Such passive tracers are considered for two important anthropogenic sources, Europe and eastern North America. The linearity of passive tracer continuity allows ...

Mark Holzer

1999-06-01T23:59:59.000Z

452

Tracer Testing At Jemez Pueblo Area (DOE GTP) | Open Energy Informatio...  

Open Energy Info (EERE)

Tracer Testing At Jemez Pueblo Area (DOE GTP) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Tracer Testing At Jemez Pueblo Area (DOE GTP)...

453

Quantum Thermodynamics  

E-Print Network (OSTI)

Quantum thermodynamics addresses the emergence of thermodynamical laws from quantum mechanics. The link is based on the intimate connection of quantum thermodynamics with the theory of open quantum systems. Quantum mechanics inserts dynamics into thermodynamics giving a sound foundation to finite-time-thermodynamics. The emergence of the 0-law I-law II-law and III-law of thermodynamics from quantum considerations is presented. The emphasis is on consistence between the two theories which address the same subject from different foundations. We claim that inconsistency is the result of faulty analysis pointing to flaws in approximations.

Ronnie Kosloff

2013-05-10T23:59:59.000Z

454

UltraDots Inc formely UltraPhotonics | Open Energy Information  

Open Energy Info (EERE)

UltraDots Inc formely UltraPhotonics UltraDots Inc formely UltraPhotonics Jump to: navigation, search Name UltraDots Inc (formely UltraPhotonics ) Place Fremont, California Zip CA 94539 Product Nanotechnology company developing "quantum dot" technology for a range of energy, communications and medical applications. Originally included photovoltaics, but this application seems to no longer be the focus. Coordinates 44.2605°, -88.880509° Loading map... {"minzoom":false,"mappingservice":"googlemaps3","type":"ROADMAP","zoom":14,"types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"geoservice":"google","maxzoom":false,"width":"600px","height":"350px","centre":false,"title":"","label":"","icon":"","visitedicon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"wmsoverlay":"","layers":[],"controls":["pan","zoom","type","scale","streetview"],"zoomstyle":"DEFAULT","typestyle":"DEFAULT","autoinfowindows":false,"kml":[],"gkml":[],"fusiontables":[],"resizable":false,"tilt":0,"kmlrezoom":false,"poi":true,"imageoverlays":[],"markercluster":false,"searchmarkers":"","locations":[{"text":"","title":"","link":null,"lat":44.2605,"lon":-88.880509,"alt":0,"address":"","icon":"","group":"","inlineLabel":"","visitedicon":""}]}

455

Tracer Gas Transport under Mixed Convection Conditions in an Experimental  

NLE Websites -- All DOE Office Websites (Extended Search)

Tracer Gas Transport under Mixed Convection Conditions in an Experimental Tracer Gas Transport under Mixed Convection Conditions in an Experimental Atrium: Comparison Between Experiments and CFD Predictions Title Tracer Gas Transport under Mixed Convection Conditions in an Experimental Atrium: Comparison Between Experiments and CFD Predictions Publication Type Journal Article Year of Publication 2006 Authors Jayaraman, Buvaneswari, Elizabeth U. Finlayson, Michael D. Sohn, Tracy L. Thatcher, Phillip N. Price, Emily E. Wood, Richard G. Sextro, and Ashok J. Gadgil Journal Atmospheric Environment Volume 40 Start Page Chapter Pagination 5236-5250 Keywords airflow and pollutant transport group, atria, indoor airflow and pollutant transport, indoor environment department, indoor pollutant dispersion, mixed convection, turbulence model

456

Some design considerations for the proposed Dixie Valley tracer test  

DOE Green Energy (OSTI)

A tracer test for the Dixie Valley, Nevada, geothermal resource is planned for the summer of 1988, in order to study the fluid flow paths that will develop under typical operating conditions. During the test six production wells will provide the power plant with steam sufficient for generation of 60 MWe, requiring fluid production at a rate of approximately 600 kg/sec. Up to 75% by mass of the extracted fluid will be reinjected into the reservoir, using four injection wells. Tracer will be added to the injected fluid for a twenty-minute period, and subsequently the produced fluid will be monitored for the tracer. 5 refs., 9 figs., 5 tabs.

Doughty, C.; Bodvarsson, G.S.

1988-06-01T23:59:59.000Z

457

Quantum Histories and Quantum Gravity  

E-Print Network (OSTI)

This paper reviews the histories approach to quantum mechanics. This discussion is then applied to theories of quantum gravity. It is argued that some of the quantum histories must approximate (in a suitable sense) to classical histories, if the correct classical regime is to be recovered. This observation has significance for the formulation of new theories (such as quantum gravity theories) as it puts a constraint on the kinematics, if the quantum/classical correspondence principle is to be preserved. Consequences for quantum gravity, particularly for Lorentz symmetry and the idea of "emergent geometry", are discussed.

Joe Henson

2009-01-26T23:59:59.000Z

458

Quantum probabilities of composite events in quantum measurements with multimode states  

E-Print Network (OSTI)

The problem of defining quantum probabilities of composite events is considered. This problem is of high importance for the theory of quantum measurements and for quantum decision theory that is a part of measurement theory. We show that the Luders probability of consecutive measurements is a transition probability between two quantum states and that this probability cannot be treated as a quantum extension of the classical conditional probability. The Wigner distribution is shown to be a weighted transition probability that cannot be accepted as a quantum extension of the classical joint probability. We suggest the definition of quantum joint probabilities by introducing composite events in multichannel measurements. The notion of measurements under uncertainty is defined. We demonstrate that the necessary condition for the mode interference is the entanglement of the composite prospect together with the entanglement of the composite statistical state. As an illustration, we consider an example of a quantum game. A special attention is payed to the application of the approach to systems with multimode states, such as atoms, molecules, quantum dots, or trapped Bose-condensed atoms with several coherent modes.

V. I. Yukalov; D. Sornette

2013-08-26T23:59:59.000Z

459

Quantum Chromodynamics  

E-Print Network (OSTI)

Quantum chromodynamics is the quantum gauge field theory that describes the strong interactions. This article reviews the basic structure, successes and challenges of quantum chromodynamics as it manifests itself at short and long distances, including the concepts of asymptotic freedom, confinement and infrared safety.

George Sterman

2005-12-27T23:59:59.000Z

460

Parity meter for charge qubits: an efficient quantum entangler  

E-Print Network (OSTI)

We propose a realization of a charge parity meter based on two double quantum dots alongside a quantum point contact. Such a device is a specific example of the general class of mesoscopic quadratic quantum measurement detectors previously investigated by Mao et al. [Phys. Rev. Lett. 93, 056803 (2004)]. Our setup accomplishes entangled state preparation by a current measurement alone, and allows the qubits to be effectively decoupled by pinching off the parity meter. Two applications of the parity meter are discussed: the measurement of Bell's inequality in charge qubits and the realization of a controlled NOT gate.

B. Trauzettel; A. N. Jordan; C. W. J. Beenakker; M. Buttiker

2006-02-22T23:59:59.000Z

Note: This page contains sample records for the topic "quantum dot tracers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


461

National Biomedical Tracer Facility: Project definition study  

SciTech Connect

The Los Alamos National Laboratory is an ideal institution and New Mexico is an ideal location for siting the National Biomedical Tracer Facility (NBTF). The essence of the Los Alamos proposal is the development of two complementary irradiation facilities that combined with our existing radiochemical processing hot cell facilities and waste handling and disposal facilities provide a low cost alternative to other proposals that seek to satisfy the objectives of the NBTF. We propose the construction of a 30 MeV cyclotron facility at the site of the radiochemical facilities, and the construction of a 100 MeV target station at LAMPF to satisfy the requirements and objectives of the NBTF. We do not require any modifications to our existing radiochemical processing hot cell facilities or our waste treatment and disposal facilities to accomplish the objectives of the NBTF. The total capital cost for the facility defined by the project definition study is $15.2 M. This cost estimate includes $9.9 M for the cyclotron and associated facility, $2.0 M for the 100 MeV target station at LAMPF, and $3.3 M for design.

Heaton, R.; Peterson, E. [Los Alamos National Lab., NM (United States); Smith, P. [Smith (P.A.) Concepts and Designs (United States)

1995-05-31T23:59:59.000Z

462

Photofragment slice imaging studies of pyrrole and the Xe{center_dot}{center_dot}{center_dot}pyrrole cluster  

SciTech Connect

The photolysis of pyrrole has been studied in a molecular beam at wavelengths of 250, 240, and 193.3 nm, using two different carrier gases, He and Xe. A broad bimodal distribution of H-atom fragment velocities has been observed at all wavelengths. Near threshold at both 240 and 250 nm, sharp features have been observed in the fast part of the H-atom distribution. Under appropriate molecular beam conditions, the entire H-atom loss signal from the photolysis of pyrrole at both 240 and 250 nm (including the sharp features) disappear when using Xe as opposed to He as the carrier gas. We attribute this phenomenon to cluster formation between Xe and pyrrole, and this assumption is supported by the observation of resonance enhanced multiphoton ionization spectra for the (Xe{center_dot}{center_dot}{center_dot}pyrrole) cluster followed by photofragmentation of the nascent cation cluster. Ab initio calculations are presented for the ground states of the neutral and cationic (Xe{center_dot}{center_dot}{center_dot}pyrrole) clusters as a means of understanding their structural and energetic properties.

Rubio-Lago, L.; Zaouris, D.; Sakellariou, Y.; Sofikitis, D.; Kitsopoulos, T. N.; Wang, F.; Yang, X.; Cronin, B.; Devine, A. L.; King, G. A.; Nix, M. G. D.; Ashfold, M. N. R.; Xantheas, S. S. [Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, 71110 Heraklion, Crete (Greece); Department of Chemistry, University of Crete, 71110 Heraklion, Crete (Greece); State Key Laboratory for Molecular Reaction Dynamics, Dalian, 116023 Liaoning (China); School of Chemistry, University of Bristol, Bristol BS8 1TS (United Kingdom); Chemical and Materials Sciences Division, Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999, MS K1-83, Richland, Washington 99352 (United States)

2007-08-14T23:59:59.000Z

463

Quantum Information Portal  

Science Conference Proceedings (OSTI)

... Quantum Devices; Quantum Information Technology; Quantum Key Distribution; ... Entangled photon generation in a phase-modulated, quasi ...

2013-10-23T23:59:59.000Z

464

RKKY Interaction and the Nature of the Ground State of Double Dots in Parallel  

Science Conference Proceedings (OSTI)

We argue through a combination of slave-boson mean-field theory and the Bethe ansatz that the ground state of closely spaced double quantum dots in parallel coupled to a single effective channel are Fermi liquids. We do so by studying the dots conductance, impurity entropy, and spin correlation. In particular, we find that the zero-temperature conductance is characterized by the Friedel sum rule, a hallmark of Fermi-liquid physics, and that the impurity entropy vanishes in the limit of zero temperature, indicating that the ground state is a singlet. This conclusion is in opposition to a number of numerical renormalization-group studies. We suggest a possible reason for the discrepancy.

Kulkarni, M.; Konik, R.

2011-06-23T23:59:59.000Z

465

Tracking thermal fronts with temperature-sensitive, chemically reactive tracers  

DOE Green Energy (OSTI)

Los Alamos is developing tracer techniques using reactive chemicals to track thermal fronts in fractured geothermal reservoirs. If a nonadsorbing tracer flowing from the injection to production well chemically reacts, its reaction rate will be a strong function of temperature. Thus the extent of chemical reaction will be greatest early in the lifetime of the system, and less as the thermal front progresses from the injection to production well. Early laboratory experiments identified tracers with chemical kinetics suitable for reservoirs in the temperature range of 75 to 100/sup 0/C. Recent kinetics studies have focused on the kinetics of hydrolysis of derivatives of bromobenzene. This class of reactions can be used in reservoirs ranging in temperature from 150 to 275/sup 0/C, which is of greater interest to the geothermal industry. Future studies will include laboratory adsorption experiments to identify possibly unwanted adsorption on granite, development of sensitive analytical techniques, and a field demonstration of the reactive tracer concept.

Robinson, B.A.; Birdsell, S.A.

1987-01-01T23:59:59.000Z

466

A Study of Tracer Distribution Parameter Estimation from Sparse Samples  

Science Conference Proceedings (OSTI)

How do design parameters such as the spacing of sampling stations affect the quality of information obtained from atmospheric dispersion experiments? In large-scale experiments such as the Cross-Appalachian Tracer Experiment (CAPTEX) and the ...

J. Z. Holland

1991-01-01T23:59:59.000Z

467

Morning Transition Tracer Experiments in a Deep Narrow Valley  

Science Conference Proceedings (OSTI)

Three sulfur hexafluoride atmospheric tracer experiments were conducted during the post-sunrise temperature inversion breakup period in the deep, narrow Brush Creek Valley of Colorado. Experiments were conducted under clear, undisturbed weather ...

C. David Whiteman

1989-07-01T23:59:59.000Z

468

Lagrangian Transport Calculations Using UARS Data. Part I. Passive Tracers  

Science Conference Proceedings (OSTI)

The transport of passive tracers observed by the Upper Atmosphere Research Satellite is simulated using computed three-dimensional trajectories of ? 100 000 air parcels initialized on a stratosphere grid, with horizontal winds provided by the ...

G.L. Manney; R.W. Zurek; W.A. Lahoz; R.S. Harwood; J.C. Gille; J.B. Kumer; J.L. Mergenthaler; A.E. Roche; A. O'Neill; R. Swinbank; J.W. Waters

1995-09-01T23:59:59.000Z

469

Ventilation Rates Estimated from Tracers in the Presence of Mixing  

Science Conference Proceedings (OSTI)

The intimate relationship among ventilation, transit-time distributions, and transient tracer budgets is analyzed. To characterize the advective–diffusive transport from the mixed layer to the interior ocean in terms of flux we employ a ...

Timothy M. Hall; Thomas W. N. Haine; Darryn W. Waugh; Mark Holzer; Francesca Terenzi; Deborah A. LeBel

2007-11-01T23:59:59.000Z

470

The Dispersion of Atmospheric Tracers in Nocturnal Drainage Flows  

Science Conference Proceedings (OSTI)

This paper summarizes the results of a series of perfluorocarbon tracer experiments that were carried out in the Brush Creek Valley in western Colorado under the auspices of the Atmospheric Studies in Complex Terrain (ASCOT) program. The results ...

Paul H. Gudiksen; Donald L. Shearer

1989-07-01T23:59:59.000Z

471

Diagnosis of Subtropical Humidity Dynamics Using Tracers of Last Saturation  

Science Conference Proceedings (OSTI)

A technique for diagnosing the mechanisms that control the humidity in a general circulation model (GCM) or observationally derived meteorological analysis dataset is presented. The technique involves defining a large number of tracers, each of ...

Joseph Galewsky; Adam Sobel; Isaac Held

2005-09-01T23:59:59.000Z

472

Atmospheric Dispersion and Tracer Ventilation in a Deep Mountain Valley  

Science Conference Proceedings (OSTI)

During September and October 1984, a major meteorological and tracer study was conducted in Colorado's Brush Creek valley. The characteristics of atmospheric dispersion during the nighttime and morning transition periods are discussed in this ...

K. Jerry Allwine

1993-06-01T23:59:59.000Z

473

An Automated Sequential Syringe Sampler for Atmospheric Tracer Studies  

Science Conference Proceedings (OSTI)

The design of an improved sampler for the automatic collection of air samples during atmospheric halogenated tracer experiments is described. In this approach, each sample is collected in a small volume (20 to 150 ml) syringe using a rack and ...

Joseph P. Krasnec; David E. Demaray; Brian Lamb; Richard Benner

1984-12-01T23:59:59.000Z

474

Tracer Advection Using Dynamic Grid Adaptation and MM5  

Science Conference Proceedings (OSTI)

A dynamic grid adaptation (DGA) technique is used to numerically simulate tracer transport at meso- and regional scales. A gridpoint redistribution scheme is designed to maximize heuristic characteristics of a “good” grid. The advective solver ...

John P. Iselin; William J. Gutowski; Joseph M. Prusa

2005-01-01T23:59:59.000Z

475

Can a Tracer Field Be Inverted for Velocity?  

Science Conference Proceedings (OSTI)

Determining flow fields and mixing rates from chemical tracer distributions is a challenging and important oceanographic problem. Thus the conclusion, that solutions obtained for underdetermined systems were “devoid of physical content”, drawn by ...

Carl Wunsch

1985-11-01T23:59:59.000Z

476

Geographic Information Systems- Tools For Geotherm Exploration, Tracers  

Open Energy Info (EERE)

Systems- Tools For Geotherm Exploration, Tracers Systems- Tools For Geotherm Exploration, Tracers Data Analysis, And Enhanced Data Distribution, Visualization, And Management Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Conference Paper: Geographic Information Systems- Tools For Geotherm Exploration, Tracers Data Analysis, And Enhanced Data Distribution, Visualization, And Management Details Activities (4) Areas (3) Regions (0) Abstract: Geographic information systems (GIS) are an underused resource that can help the geothermal industry in exploration, tracer analysis, infrastructure management, and the general distribution and use of data. GIS systems are highly customizable to specific user needs and can use entire corporate data sets through a visual interface. This paper briefly documents the use of GIS in specific examples of geothermal research at the

477

Preferred methods of analysis for chemical tracers in moderate- and  

Open Energy Info (EERE)

Preferred methods of analysis for chemical tracers in moderate- and Preferred methods of analysis for chemical tracers in moderate- and high-temperature geothermal environments Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Report: Preferred methods of analysis for chemical tracers in moderate- and high-temperature geothermal environments Details Activities (2) Areas (2) Regions (0) Abstract: This report describes the sampling and analytical techniques used for tracer analysis in the Raft River and East Mesa field tests. The collection procedures and sample preservation techniques, analytical methods and possible sources of contamination or error are discussed in detail. Author(s): Kroneman, R. L.; Yorgason, K. R.; Moore, J. N. Published: DOE Information Bridge, 12/1/1984 Document Number: Unavailable DOI: 10.2172/5121460

478

Quantitative interpretation of tracer test data | Open Energy Information  

Open Energy Info (EERE)

Quantitative interpretation of tracer test data Quantitative interpretation of tracer test data Jump to: navigation, search OpenEI Reference LibraryAdd to library Conference Paper: Quantitative interpretation of tracer test data Abstract Geothermal reinjection is an important part of sustainable management of geothermal resources. Reinjection started out as a method of waste-water disposal, but is now also being used to counteract pressure draw-down and to extract more thermal energy from reservoir rocks. The possible cooling of production wells, or thermal breakthrough, is one of the main disadvantages associated with injection. To minimize this danger while maintaining the benefit from reinjection requires careful testing and research. Tracer testing, which is used to study flow-paths and quantify fluid-flow in hydrological systems, is probably the most important tool for

479

Transport of Passive Tracers in Baroclinic Wave Life Cycles  

Science Conference Proceedings (OSTI)

The transport of passive tracers in idealized baroclinic wave life cycles is studied using output from the National Center for Atmospheric Research Community Climate Model (CCM2). Two life cycles, LCn and LCs, are simulated, starting with ...

Elizabeth M. Stone; William J. Randel; John L. Stanford

1999-05-01T23:59:59.000Z

480

Quantum bundles and quantum interactions  

E-Print Network (OSTI)

A geometric framework for describing quantum particles on a possibly curved background is proposed. Natural constructions on certain distributional bundles (`quantum bundles') over the spacetime manifold yield a quantum ``formalism'' along any 1-dimensional timelike submanifold (a `detector'); in the flat, inertial case this turns out to reproduce the basic results of the usual quantum field theory, while in general it could be seen as a local, ``linearized'' description of the actual physics.

Daniel Canarutto

2005-06-22T23:59:59.000Z

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481

Quantum Cosmology  

E-Print Network (OSTI)

We give an introduction into quantum cosmology with emphasis on its conceptual parts. After a general motivati