Evolution of crystal structure properties of In0.4Ga0.6N thin-film under varying powers

Abstract

In0.4Ga0.6N thin films were coated on GaN/p-Si substrates by radio frequency magnetron (RFM) sputter under 40, 60, 80, 100, 120 W applied power. Crystal-structure properties of resulting InGaN films showed significant changes corresponding to changes in applied power values. Also, increasing power from 100 to 120 W resulted in an increasing film texture coefficient (from 1.42 to 1.55). Thin films with GaN, InN, InNxOy, and In2O3 bonds were detected from X-ray photoelectron spectroscopy (XPS) measurements. Increasing power yielded a decrease in the optical bandgap (direct -allowed) from about 2.58 to 2.49 eV mainly due to the increasing grain sizes of the thin film. It was found that the optical conductivity of the films showed different behaviors under various applied powers. The general trend in the atomic force microscopy (AFM) results showed that surface roughness increased with increasing power. Overall, how varying power values cause crystal structures to evolve and some physical parameters of thin film are discussed. © 2021