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Title: Enhanced Materials Based on Submonolayer Type-II Quantum Dots

Abstract

We have investigated a nanostructured material known as sub-monolayer type-II QDs, made from wide bandgap II-VI semiconductors. Our goal is to understand and exploit their tunable optical and electrical properties by taking advantage of the type-II band alignment and quantum confinement effects. Type-II ZnTe quantum dots (QDs) in a ZnSe host are particularly interesting because of their relatively large valence band and conduction band offsets. In the current award we have developed new materials based on sub-monolayer type-II QDs that may be advantageous for photovoltaic and spintronics applications. We have also expanded the structural characterization of these materials by refining the X-ray diffraction methodologies needed to investigate them. In particular, we have 1) demonstrated ZnCdTe/ZnCdSe type-II QDs materials that have ideal properties for the development of novel high efficiency “intermediate band solar cells”, 2) we developed a comprehensive approach to describe and model the growth of these ultra-small type-II QDs, 3) analysis of the evolution of the photoluminescence (PL) emission, combined with other characterization probes allowed us to predict the size and density of the QDs as a function of the growth conditions, 4) we developed and implemented novel sophisticated X-ray diffraction techniques from which accurate size and shape ofmore » the buried type-II QDs could be extracted, 5) a correlation of the shape anisotropy with polarization dependent PL was observed, confirming the QDs detailed shape and providing insight about the effects of this shape anisotropy on the physical properties of the type-II QD systems, and 6) a detailed “time-resolved Kerr rotation” investigation has led to the demonstration of enhanced electron spin lifetimes for the samples with large densities of type-II QDs and an understanding of the interplay between the QDs and Te-isoelectroic centers, a defect that forms in the spacer layers that separate the QDs.« less

Authors:
 [1];  [2];  [1];  [3]
  1. City College of New York, NY (United States)
  2. City Univ. (CUNY), NY (United States) Queens College
  3. Columbia Univ., New York, NY (United States)
Publication Date:
Research Org.:
City College of New York, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Contributing Org.:
The City College of New York, Queens College of CUNY and Columbia University
OSTI Identifier:
1351806
Report Number(s):
DOE-CCNY-0003739-1
DOE Contract Number:
SC0003739
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 77 NANOSCIENCE AND NANOTECHNOLOGY; 30 DIRECT ENERGY CONVERSION; II-VI semiconductors; type-II quantum dots; photovoltaics; intermediate band solar cell

Citation Formats

Tamargo, Maria C, Kuskovsky, Igor L., Meriles, Carlos, and Noyan, Ismail C. Enhanced Materials Based on Submonolayer Type-II Quantum Dots. United States: N. p., 2017. Web. doi:10.2172/1351806.
Tamargo, Maria C, Kuskovsky, Igor L., Meriles, Carlos, & Noyan, Ismail C. Enhanced Materials Based on Submonolayer Type-II Quantum Dots. United States. doi:10.2172/1351806.
Tamargo, Maria C, Kuskovsky, Igor L., Meriles, Carlos, and Noyan, Ismail C. Sat . "Enhanced Materials Based on Submonolayer Type-II Quantum Dots". United States. doi:10.2172/1351806. https://www.osti.gov/servlets/purl/1351806.
@article{osti_1351806,
title = {Enhanced Materials Based on Submonolayer Type-II Quantum Dots},
author = {Tamargo, Maria C and Kuskovsky, Igor L. and Meriles, Carlos and Noyan, Ismail C.},
abstractNote = {We have investigated a nanostructured material known as sub-monolayer type-II QDs, made from wide bandgap II-VI semiconductors. Our goal is to understand and exploit their tunable optical and electrical properties by taking advantage of the type-II band alignment and quantum confinement effects. Type-II ZnTe quantum dots (QDs) in a ZnSe host are particularly interesting because of their relatively large valence band and conduction band offsets. In the current award we have developed new materials based on sub-monolayer type-II QDs that may be advantageous for photovoltaic and spintronics applications. We have also expanded the structural characterization of these materials by refining the X-ray diffraction methodologies needed to investigate them. In particular, we have 1) demonstrated ZnCdTe/ZnCdSe type-II QDs materials that have ideal properties for the development of novel high efficiency “intermediate band solar cells”, 2) we developed a comprehensive approach to describe and model the growth of these ultra-small type-II QDs, 3) analysis of the evolution of the photoluminescence (PL) emission, combined with other characterization probes allowed us to predict the size and density of the QDs as a function of the growth conditions, 4) we developed and implemented novel sophisticated X-ray diffraction techniques from which accurate size and shape of the buried type-II QDs could be extracted, 5) a correlation of the shape anisotropy with polarization dependent PL was observed, confirming the QDs detailed shape and providing insight about the effects of this shape anisotropy on the physical properties of the type-II QD systems, and 6) a detailed “time-resolved Kerr rotation” investigation has led to the demonstration of enhanced electron spin lifetimes for the samples with large densities of type-II QDs and an understanding of the interplay between the QDs and Te-isoelectroic centers, a defect that forms in the spacer layers that separate the QDs.},
doi = {10.2172/1351806},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sat Apr 15 00:00:00 EDT 2017},
month = {Sat Apr 15 00:00:00 EDT 2017}
}

Technical Report:

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