Computational study and characteristics of In2S3 thin films: effects of substrate nature and deposition temperature

Abstract

In this work, we investigate the effects of both growth temperature and substrate nature on different properties of indium sulfide thin films prepared by chemical vapor deposition method using triphenylphosphine sulfide as a sulfur precursor. The structural, morphological, and optical properties of the resulting thin films were characterized using x-ray diffraction, scanning electron microscopy (SEM) and UV–vis spectroscopy respectively. The structural study has proved that pure nanocrsytalline β-indium sulfide films were obtained at 300 and 400 °C regardless of the substrate nature, while higher growth temperature (500 °C) leads to the formation of pure indium oxide films. From the SEM images, it is derived that the surface morphology of the obtained films was independent to both growth temperature and substrate nature. The electronic structure of β-In2S3 was computed using density functional theory calculations. The optical properties of the obtained films such as energy band-gap, extinction coefficient, refractive index, dielectric constant and optical conductivity were investigated theoretically and experimentally. It was shown that these parameters were mainly controlled by the substrate type and the phase formed. The theoretical optical investigation was in full agreement with the experimental results. Oscillator energy, dispersion energy and Urbach energy were also estimated. Blue and violet PL emissions indicate the useful application of the obtained films as blue and violet light emitters.