Visible photoluminescence from nanocrystalline Ge grown at room temperature by photo-oxidation of SiGe using a 126 nm lamp

Abstract

In this paper, for the first time, we report rapid photo-oxidation of SiGe at room temperature using a 126 nm excimer lamp. The structure and composition of the oxidized layers were investigated by Fourier transform infrared spectroscopy (FTIR), ellipsometry, and X-ray photoelectron spectroscopy (XPS), while their electrical properties were determined by current–voltage and capacitance–voltage measurements. The XPS and FTIR investigations showed that the layers grown for shorter periods of time contain SiO 2. Most of Ge atoms initially present in the surface layer were segregated and accumulated at the interface between the grown oxide and remaining SiGe. (PL) spectra of the Ge nanocrystals were measured by using 454.5–514.5 nm excitation light from an Ar ion laser. FTIR spectra of the oxidized SiGe samples exhibited the Si–O stretching absorption band of SiO 2 around 1070 cm −1 for different exposure times (30, 60, 120, 240 s). It was found that post UV annealing at 400 °C in oxygen could significantly increase the intensity and stabilise the visible PL. The intensity ratio of the 600/655 nm peaks in the PL spectra decreases with annealing time, indicating an increase in the size of the nanoparticles.