InP (and GaAs) substrate stabilization by the presence of GaAs (and InP) in a metal-organic vapour-phase epitaxy system

Abstract

Metal-organic vapour-phase epitaxy (MOVPE) is a well-established technique for semiconductor growth. Like molecular-beam epitaxy, liquid-phase epitaxy, and vapour-phase epitaxy, it requires a stabilized substrate surface prior to growth to obtain a high-quality crystal. Studies of the stabilization of GaAs and InP substrates placed side by side with their interactions under V-hydride flows can provide valuable information. Here we show the effect of exposing GaAs and InP substrates to AsH3 and (or) PH3 in the temperature range from 550 °C to 750 °C, in an MOVPE reactor. The presence of a GaAs substrate partially stabilizes the InP substrate; the stabilized area decreases when either temperature of AsH3 flow increases. The presence of a stabilized InP substrate (under PH3 flow) also partially stabilizes the GaAs substrate. Surface analysis shows that the stabilized area contains column-V species coming from the neighbouring substrate. These column-V species are competing with species originating from the V hydrides (AsH3 or PH3). From the analysis of these experiments, we conclude that the V-hydride species active in the MOVPE environment are not dimers or tetramers. Annealing the substrates under both AsH3, and PH3 shows preference for As-specics aggregation at the substrate surface. The simple model previously used to prediet stabilization is extended to cover this mixed-hydride situation.