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Title: Experimental Imaging and Atomistic Modeling of Electron and Hole Quasiparticle Wave Functions In InAs/GaAs Quantum Dots

Abstract

We present experimental magnetotunneling results and atomistic pseudopotential calculations of quasiparticle electron and hole wave functions of self-assembled InAs/GaAs quantum dots. The combination of a predictive theory along with the experimental results allows us to gain direct insight into the quantum states. We monitor the effects of (i) correlations, (ii) atomistic symmetry, and (iii) piezoelectricity on the confined carriers and (iv) observe a peculiar charging sequence of holes that violates the Aufbau principle.

Authors:
; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
939534
DOE Contract Number:
AC36-99-GO10337
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. B, Condensed Matter and Materials Physics; Journal Volume: 76; Journal Issue: 7, 2007; Related Information: Article No. 075338
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; AUFBAU PRINCIPLE; ELECTRONS; MONITORS; PIEZOELECTRICITY; QUANTUM DOTS; SIMULATION; SYMMETRY; WAVE FUNCTIONS; Basic Sciences

Citation Formats

Bester, G., Reuter, D., He. L., Zunger, A., Kailuweit, P., Wieck, A. D., Zeitler, U., Maan, J. C., Wibbelhoff, O., and Lorke, A.. Experimental Imaging and Atomistic Modeling of Electron and Hole Quasiparticle Wave Functions In InAs/GaAs Quantum Dots. United States: N. p., 2007. Web. doi:10.1103/PhysRevB.76.075338.
Bester, G., Reuter, D., He. L., Zunger, A., Kailuweit, P., Wieck, A. D., Zeitler, U., Maan, J. C., Wibbelhoff, O., & Lorke, A.. Experimental Imaging and Atomistic Modeling of Electron and Hole Quasiparticle Wave Functions In InAs/GaAs Quantum Dots. United States. doi:10.1103/PhysRevB.76.075338.
Bester, G., Reuter, D., He. L., Zunger, A., Kailuweit, P., Wieck, A. D., Zeitler, U., Maan, J. C., Wibbelhoff, O., and Lorke, A.. Mon . "Experimental Imaging and Atomistic Modeling of Electron and Hole Quasiparticle Wave Functions In InAs/GaAs Quantum Dots". United States. doi:10.1103/PhysRevB.76.075338.
@article{osti_939534,
title = {Experimental Imaging and Atomistic Modeling of Electron and Hole Quasiparticle Wave Functions In InAs/GaAs Quantum Dots},
author = {Bester, G. and Reuter, D. and He. L. and Zunger, A. and Kailuweit, P. and Wieck, A. D. and Zeitler, U. and Maan, J. C. and Wibbelhoff, O. and Lorke, A.},
abstractNote = {We present experimental magnetotunneling results and atomistic pseudopotential calculations of quasiparticle electron and hole wave functions of self-assembled InAs/GaAs quantum dots. The combination of a predictive theory along with the experimental results allows us to gain direct insight into the quantum states. We monitor the effects of (i) correlations, (ii) atomistic symmetry, and (iii) piezoelectricity on the confined carriers and (iv) observe a peculiar charging sequence of holes that violates the Aufbau principle.},
doi = {10.1103/PhysRevB.76.075338},
journal = {Physical Review. B, Condensed Matter and Materials Physics},
number = 7, 2007,
volume = 76,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • A model for realistic InAs quantum dot composition profile is proposed and analyzed, consisting of a double region scheme with an In-rich internal core and an In-poor external shell, in order to mimic the atomic scale phenomena such as In-Ga intermixing and In segregation during the growth and overgrowth with GaAs. The parameters of the proposed model are derived by reproducing the experimentally measured polarization data. Further understanding is developed by analyzing the strain fields which suggests that the two-composition model indeed results in lower strain energies than the commonly applied uniform composition model.
  • InAs/GaAs quantum dots (QD's) are formed by postgrowth annealing of an InAs wetting layer thinner than the critical thickness for the transition from two- (2D) to three-dimensional (3D) growth mode. Reflection high energy electron diffraction is used to monitor the QD formation. Based on a mean-field theory [Phys. Rev. Lett. 79, 897 (1997)], the time evolution of total QD's volume, first increasing and finally saturating, is well explained by precursors forming during wetting layer growth and converting into nucleated QD's after growth stop. Both the saturation QD's volume and the QD nucleation rate depend exponentially on the InAs coverage. Thesemore » behaviors and their temperature and InAs growth rate dependences are essentially understandable in the frame of the mean-field theory. Similar analysis to conventional QD growth suggests that the often observed significant mass transport from wetting layer to QD's can be ascribed to the precursors existing before 2D-3D growth mode transition.« less
  • Excitons in quantum dots manifest a lower-energy spin-forbidden 'dark' state below a spin-allowed 'bright' state; this splitting originates from electron-hole (e-h) exchange interactions, which are strongly enhanced by quantum confinement. The e-h exchange interaction may have both a short-range and a long-range component. Calculating numerically the e-h exchange energies from atomistic pseudopotential wave functions, we show here that in direct-gap quantum dots (such as InAs) the e-h exchange interaction is dominated by the long-range component, whereas in indirect-gap quantum dots (such as Si) only the short-range component survives. As a result, the exciton dark/bright splitting scales as 1/R{sup 2} inmore » InAs dots and 1/R{sup 3} in Si dots, where R is the quantum-dot radius.« less
  • We report on quantum dot (QD) lasers made of stacked InAs dots grown by metalorganic chemical vapor deposition. Successful growth of defect-free binary InAs/GaAs QDs with high lateral density (d{sub l}{ge}4{times}10{sup 10}cm{sup {minus}2}) was achieved in a narrow growth parameter window. The room-temperature photoluminescence (PL) intensity is enhanced up to a factor of 3 and the PL peak width is reduced by more than 30{percent} when a thin layer of In{sub 0.3}Ga{sub 0.7}As is deposited onto the InAs QDs. A QD laser with a single sheet of such InAs/InGaAs/GaAs QDs exhibits threshold current densities as low as 12.7 and 181A/cm{supmore » 2} at 100 and 300 K, respectively. Lasers with threefold stacked QDs show ground-state lasing and allow for cw operation at room temperature. {copyright} {ital 1997 American Institute of Physics.}« less