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Title: Structure, strain, and composition profiling of InAs/GaAs(211)B quantum dot superlattices

The morphology, nanostructure, and strain properties of InAs quantum dots (QDs) grown on GaAs(211)B, uncapped or buried, are explored by transmission electron microscopy and related quantitative techniques. Besides the built-in piezoelectric field, other differences of (211) growth compared to (100)-oriented growth are discussed in terms of the (211) surface non-singularity, leading to anisotropic shape of the QDs and local chemical inhomogeneity of the wetting layer. The shape of the uncapped QDs was precisely defined as truncated pyramidal, elongated along the 〈111〉 direction, and bounded by the (110), (100), and (213) facets. Local strain measurements showed that large surface QDs were almost unstrained due to plastic relaxation, exhibiting small residual elastic strain at the interface that gradually diminished toward their apex. Conversely, buried QDs were pseudomorphically grown on GaAs. By postulating a plane stress state, we have established a systematic increase of the local strain from the base toward the apex region of the QDs. Using Vegard's law, their chemical composition profiles were calculated, revealing an indium content gradient along the growth direction and compositional variants among different QDs. Photoluminescence measurements showed variations in emission energy between the QDs and consistency with a graded In-content, which complied with the quantitative strainmore » analysis.« less
Authors:
; ; ;  [1] ; ;  [2] ;  [3] ;  [2] ;  [4] ;  [3]
  1. Physics Department, Aristotle University of Thessaloniki, 54624 Thessaloniki (Greece)
  2. Department of Materials Science and Technology, University of Crete, P.O. Box 2208, 70013 Heraklion (Greece)
  3. (Greece)
  4. Microelectronics Research Group, IESL-FORTH, P.O. Box 1385, 71110 Heraklion (Greece)
Publication Date:
OSTI Identifier:
22494927
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 119; Journal Issue: 3; Other Information: (c) 2016 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ANISOTROPY; CHEMICAL COMPOSITION; GALLIUM ARSENIDES; INDIUM ARSENIDES; INTERFACES; LAYERS; MORPHOLOGY; PHOTOLUMINESCENCE; PIEZOELECTRICITY; QUANTUM DOTS; RELAXATION; SHAPE; SINGULARITY; STRAINS; SUPERLATTICES; TRANSMISSION ELECTRON MICROSCOPY