X-ray photoemission and photoreflectance study of Au/ultrathin Si/ n-GaAs Schottky contacts and hydrogen plasma treated semi-insulating GaAs surfaces

Abstract

The paper presents room temperature photoreflectance measurements carried out on the Au/ultrathin Si/ n-crystalline GaAs structure with the silicon interlayer thickness gradually changing from about 4–27 Å prepared in situ under ultra-high-vacuum conditions, A continuous change of the phase shift of the corresponding photoreflectance signal of more than 180 degrees has been observed in the Eg-critical-pointoscillation of GaAs depending on the Si interlayer thickness. The explanation of the effect is based on the composition changes of the Au/Si interface monitored by X-ray photoelectron spectroscopy. The photoreflectance results are compared to the photoreflectance signal phase changes observed on the semi-insulating GaAs surfaces exposed to the low-temperature hydrogen plasma.