Effect of Light Irradiation on Sulfide-Treated GaAs with SiO2 Deposition

Abstract
The degradation mechanism of sulfide-treated and SiO2 deposited GaAs has been studied. The sulfide treatment removes the oxide of GaAs and Ga-dangling bonds, and increases the intensity of photoluminescence. However, by the irradiation of UV light or Ar+ laser, the photoluminescence intensity is reduced substantially. X-ray Photoelectron Spectroscopy (XPS) analysis and C-V measurement show that the Ga–S bonds generated by the sulfide treatment become Ga-dangling bonds due to the light irradiation. We believe this is the reason why the photoluminescence intensity decreases, and therefore, it is necessary to avoid light irradiation after sulfide treatment and SiO2 deposition on GaAs in order to maintain the surface-passivation effect.