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Title: Unexpected bismuth concentration profiles in metal-organic vapor phase epitaxy-grown Ga(As{sub 1−x}Bi{sub x})/GaAs superlattices revealed by Z-contrast scanning transmission electron microscopy imaging

A set of GaAs{sub 1−x}Bi{sub x}/GaAs multilayer quantum-well structures was deposited by metal-organic vapor phase epitaxy at 390 °C and 420 °C. The precursor fluxes were introduced with the intent of growing discrete and compositionally uniform GaAs{sub 1−x}Bi{sub x} well and GaAs barrier layers in the epitaxial films. High-resolution high-angle annular-dark-field (or “Z-contrast”) scanning transmission electron microscopy imaging revealed concentration profiles that were periodic in the growth direction, but far more complicated in shape than the intended square wave. The observed composition profiles could explain various reports of physical properties measurements that suggest compositional inhomogeneity in GaAs{sub 1−x}Bi{sub x} alloys as they currently are grown.
Authors:
;  [1] ; ; ; ;  [2]
  1. Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)
  2. Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)
Publication Date:
OSTI Identifier:
22415262
Resource Type:
Journal Article
Resource Relation:
Journal Name: APL materials; Journal Volume: 3; Journal Issue: 3; Other Information: (c) 2015 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 77 NANOSCIENCE AND NANOTECHNOLOGY; BISMUTH COMPOUNDS; CONCENTRATION RATIO; DEPLETION LAYER; FILMS; GALLIUM ARSENIDES; ORGANOMETALLIC COMPOUNDS; PERIODICITY; PHYSICAL PROPERTIES; QUANTUM WELLS; SUPERLATTICES; TEMPERATURE DEPENDENCE; TRANSMISSION ELECTRON MICROSCOPY; VAPOR PHASE EPITAXY