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

Journal Article · Thu May 14 00:00:00 EDT 2015 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4919896· OSTI ID:22410189

Wu, M.; Trampert, A. ^[1]; Puustinen, J.; Guina, M. ^[2]

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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)

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.

• OSTI ID: 22410189
• Journal Information: Journal of Applied Physics, Vol. 117, Issue 18; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

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