Influence of GaAs surface termination on GaSb/GaAs quantum dot structure and band offsets

E. S. Zech, A. S. Chang, A. J. Martin, J. C. Canniff, Y. H. Lin, J. M. Millunchick, R. S. Goldman
2013 Applied Physics Letters  
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
more » ... rface 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. V C 2015 AIP Publishing LLC.
doi:10.1063/1.4818270 fatcat:txm4snbqezh3nbxjuuy6qba3t4