Morphology of GaAs crystals heterogeneously integrated on nominal (001) Si by epitaxial lateral overgrowth on tunnel oxide via Ge nano-seeding

Publication date: 1 February 2018
Source:Thin Solid Films, Volume 647
Author(s): Marie Coste, Timothée Molière, Nikolay Cherkashin, Géraldine Hallais, Laëtitia Vincent, Daniel Bouchier, Charles Renard
In this study, GaAs crystals were grown by chemical beam epitaxy on nominal (001) Si substrate over Ge nano-seeds placed within nano-holes opened through a 0.6nm silica layer. GaAs crystal morphology and atomic organization at the interface between Ge and GaAs were studied by using complementary Scanning Transmission Electron Microscopy, energy dispersive X-ray spectrometry and dark-field electron holography. Fourfold symmetry GaAs crystals were obtained and found to be completely relaxed and twin free. Thus, the use of Ge nano-seeds to initiate the growth of GaAs results in the suppression of twins previously observed for direct GaAs growth on nominal (001) Si. Nevertheless, anti-phase domains were detected. A simple atomistic model is proposed which explains how Anti-Phase Boundaries develop at the junctions between Ge {113} facets, and {113} and {111} facets for As-stabilized GaAs growth.