A comprehensive examination of the molecular-beam epitaxy of III-V compound semiconductors through shadow masks was presented. Based upon model calculations and growth experiments, a study was made of how surface diffusion and the incorporation of group-III adatoms depended upon the growth configuration, group-III and group-V fluxes and the crystal orientation. According to a macroscopic diffusion model, the gradients of the group-V flux drove the unidirectional migration of group-III adatoms. Although this effect was generally observed, the differing growth profiles obtained for [1¯10]- and [110]-oriented samples reflected the different roles played by A-type and B-type steps in the incorporation of group-III adatoms. It was also demonstrated that, during the hetero-epitaxial growth of InAs, dissociation of the GaAs substrate was locally enhanced by the incidence of the In beam. This effect could be exploited for the shadow-mask assisted etching of selected areas. In addition, it was shown how the positions and sizes of III-V nanostructures could be controlled - to high precision - on a planar substrate by the use of shadow masks with multiple nanoscale apertures.

Surface Diffusion during Shadow-Mask Assisted Molecular-Beam Epitaxy of III-V Compounds. T.Schallenberg, K.Brunner, T.Borzenko, L.W.Molenkamp, G.Karczewski: Journal of Applied Physics, 2005, 98[1], 014903 (8pp)