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Title: Spontaneous formation of nanostructures by surface spinodal decomposition in GaAs{sub 1−x}Bi{sub x} epilayers

We report on the spontaneous formation of lateral composition modulations (LCMs) in Ga(As,Bi) epilayers grown by low-temperature (<300 °C) molecular beam epitaxy (MBE) on GaAs(001). Both cross-section and plan-view transmission electron microscopy techniques are used to investigate the nature of the LCMs, consisting of Bi-rich cylinder-like nanostructures lying along the [001] growth direction. The observed LCMs are the consequence of a two-dimensional phase separation process occurring at the surface of the growing epilayers, and their columnar nature is consistent with a surface-directed spinodal decomposition process. Although LCMs are thermodynamically driven, we show how they can be kinetically controlled, in particular, through the As/Ga flux ratio and the substrate temperature. This is a result of LCMs developing from surface atomic diffusion processes, since the atomic dimer configurations on the surface alter adatom diffusivity. The significant role of the surface reconstructions is also discussed.
Authors:
; ;  [1] ; ;  [2]
  1. Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, D-10117 Berlin (Germany)
  2. Optoelectronics Research Centre, Tampere University of Technology, P.O. Box 692, FI- 33101 Tampere (Finland)
Publication Date:
OSTI Identifier:
22410189
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 18; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; BISMUTH COMPOUNDS; CRYSTAL STRUCTURE; DIFFUSION; DIMERS; GALLIUM ARSENIDES; MODULATION; MOLECULAR BEAM EPITAXY; NANOSTRUCTURES; SEPARATION PROCESSES; SUBSTRATES; SURFACES; TEMPERATURE DEPENDENCE; TRANSMISSION ELECTRON MICROSCOPY; TWO-DIMENSIONAL SYSTEMS