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Title: Variation of lattice constant and cluster formation in GaAsBi

We investigate the structural properties of GaAsBi layers grown by molecular beam epitaxy on GaAs at substrate temperatures between 220–315 °C. Irrespective of the growth temperature, the structures exhibited similar Bi compositions, and good overall crystal quality as deduced from X-Ray diffraction measurements. After thermal annealing at temperatures as low as 500 °C, the GaAsBi layers grown at the lowest temperatures exhibited a significant reduction of the lattice constant. The lattice variation was significantly larger for Bi-containing samples than for Bi-free low-temperature GaAs samples grown as a reference. Rutherford backscattering spectrometry gave no evidence of Bi diffusing out of the layer during annealing. However, dark-field and Z-contrast transmission electron microscopy analyses revealed the formation of GaAsBi clusters with a Bi content higher than in the surrounding matrix, as well as the presence of metallic As clusters. The apparent reduction of the lattice constant can be explained by a two-fold process: the diffusion of the excess As incorporated within As{sub Ga} antisites to As clusters, and the reduction of the Bi content in the GaAs matrix due to diffusion of Bi to GaAsBi clusters. Diffusion of both As and Bi are believed to be assisted by the native point defects, whichmore » are present in the low-temperature as-grown material.« less
Authors:
; ;  [1] ; ;  [2] ;  [3] ; ;  [4]
  1. Optoelectronics Research Centre, Tampere University of Technology, P.O. Box 692, FI-33101 Tampere (Finland)
  2. Paul-Drude Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin (Germany)
  3. Department of Physics and Astronomy, University of Turku, FI-20014 Turku (Finland)
  4. Department of Physics, University of Jyväskylä, P.O. Box 35, FI-40014 Jyväskylä (Finland)
Publication Date:
OSTI Identifier:
22217722
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 114; Journal Issue: 24; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ANNEALING; CRYSTALS; DIFFUSION; GALLIUM ARSENIDES; LATTICE PARAMETERS; LAYERS; MOLECULAR BEAM EPITAXY; POINT DEFECTS; REDUCTION; RUTHERFORD BACKSCATTERING SPECTROSCOPY; SEMICONDUCTOR MATERIALS; SUBSTRATES; TRANSMISSION ELECTRON MICROSCOPY; VARIATIONS; X-RAY DIFFRACTION