Effects of arsenic oxides on GaAs surfaces on photoluminescence properties of buried InGaAs quantum wells: Dependence on initial surfaces before oxidation

Abstract

We have studied the oxidation states and photoluminescence (PL) properties of GaAs(100) samples that incorporated buried InGaAs quantum well (QW) structures prepared by molecular-beam epitaxy (MBE). The surfaces of the MBE-grown GaAs(100) samples were controlled so that they were either As-rich c(4 × 4)α, Ga-rich (4 × 6) or Se-terminated (2 × 1) structures prior to oxidation. We found that the As/Ga composition ratio at the initial GaAs surface strongly affects the oxidation processes and the resultant PL properties. An oxidized sample whose initial As-rich surface contains a large amount of As oxide, has a significantly lower PL intensity than As-deficient samples. The reduction of the surface As coverage simply by preparing Ga-rich (4 × 6) and Se-terminated (2 × 1) surfaces has a positive effect on the PL properties, which is maintained even after the oxidation has progressed into deeper layers after longer air exposure, e.g., six months.