In order to fabricate abrupt hetero-interfaces of the GaAs/InGaP system by metal-organic vapour phase epitaxy, a study was made of the In atom distribution using X-ray photo-electron spectroscopy. The systematic X-ray photo-electron spectroscopy depth profile analyses revealed that the InGaP surface contained an excess amount of In atoms owing to surface segregation. The excess In atoms diffused into the GaAs layer and cause compositional mixing at the interface of GaAs on InGaP. In order to suppress the interdiffusion and surface segregation of In atoms into GaAs on InGaP, a novel gas switching sequence was developed for growing GaAs on InGaP. That is, after the growth of InGaP, only tertiarybutylphosphine was introduced, and after stopping the supply of tertiarybutylphosphine, trimethylgallium was pre-introduced to the reactor before the growth of GaAs. Then tertiarybutylarsine was allowed to flow to initiate GaAs growth. This novel gas switching sequence contributed to the formation of abrupt hetero-interfaces of GaAs on InGaP.

Control of In Surface Segregation and Inter-Diffusion in GaAs on InGaP Grown by Metal-Organic Vapor Phase Epitaxy. Y.Fukushima, T.Nakano, Y.Nakano, Y.Shimogaki: Japanese Journal of Applied Physics, 2012, 51[5], 055601