Study of the surface chemistry, surface morphology, optical, and structural properties of InGaN thin films deposited by RF magnetron sputtering

Abstract

InGaN thin films were deposited on silicon (100) single crystal substrates by RF magnetron sputtering in an Ar atmosphere, at a pressure of 8 × 10−2 Torr, by using In and GaN targets. To change the In content, x, in the InxGa1-xN ternary alloy, the substrate temperature was varied from 300 up to 500 °C. It was found that the In content decreased with increasing substrate temperature. The optical and structural properties of the InGaN thin films were correlated with the experimental deposition conditions. It was found that the band gap energy increased with the growth temperature. Photoluminescence spectra measured at 20 K showed two broad emission bands centered at 2.3 and 2.9 eV. X-ray diffraction analysis of the InGaN thin films revealed a polycrystalline structure belonging to the hexagonal phase. The surface morphology of the films was analyzed using AFM, showing that the surface roughness increased with temperature. The surface chemistry of the films, investigated by XPS, mainly indicated the formation of Ga-N and In-N bonds. Moreover, from XPS two BVM values at 1.91 and 2.74 eV were found. A depth profile analysis, performed by SIMS, revealed the distribution of In, Ga, and N from the film surface to the bulk.