Reduction in GaAs interfacial defects via structural phase variation of hydrogenated silicon films

Abstract

GaAs surface passivation involves the structural phase variation of thin hydrogenated silicon layers from amorphous to microcrystalline phases. An intermediate phase—known as a mixed phase, wherein small crystalline grains are embedded in an amorphous matrix—is identified via Raman spectra and cross-sectional transmission electron microscopy images from amongst the varying phases. When compared with amorphous and microcrystalline silicon passivation layers, mixed-phase silicon layers showed significantly enhanced radiative recombination, which was detected using photoluminescence spectra at the Si/GaAs interface. In addition, the native oxide status of the GaAs surface, owing to Ga–O and As–O bonds detected using X-ray photoelectron spectroscopy spectra, is considerably lowered owing to the mixed-phase silicon deposition. It is thus concluded that mixed-phase silicon layers show high potential for reducing GaAs interfacial defects in optoelectronic devices.