The high pressure oxidation of InP has been studied using Raman scattering in order to examine the oxidized films for the presence of elemental Group V inclusions. Thermo-dynamic analysis of the In-P-0 phase diagram predicts that InPO4 should be the only phase produced under equilibrium growth conditions. Previous literature reports however, have shown that elemental red P inclusions are present for oxidation temperatures around 500°C at nominal oxygen pressures around 1 atmosphere. This finding indicates that kinetic factors play an important role in determining the phases present in the oxidation of InP at these temperatures. Attempts to modify the kinetics by performing the oxidation at high pressure were first performed by Wilmsen et al., and their x-ray photoemission experiments were interpreted to suggest that elemental P inclusions were suppressed by the high pressure treatment. The current Raman scattering experiments clearly demonstrate that the latter conclusion is not correct; elemental red P is detected in all oxidized InP films independent of substrate doping for oxygen pressures up to ~300 atmospheres. GaAs has also been examined with Raman scattering. For GaAs the equilibrium phase diagram does predict that elemental As is an equilibrium phase, and that finding has been verified for low pressure oxidation conditions in past studies. The present study demonstrates that elemental As is also a product of oxidized GaAs films for oxygen pressures up to 300 atmospheres for n, p, Cr and undoped substrates.
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