Nanomechanical Properties of Amorphous and Polycrystalline SrTiO3 Transparent Thin Films Prepared by Ion Beam Sputtering

Abstract

Transparent SrTiO3 thin films were deposited on glass substrates by ion beam sputtering at various substrate temperatures. The structural characteristic of the deposited films shows the transition from amorphous phase to polycrystalline phase at 600 °C. The films exhibit a good transparency in the visible region (~80-85%) and a relatively smooth surface. The calculated band gaps for amorphous and polycrystalline films were ~4.20 and ~3.84 eV, respectively. The refractive index of the films increases with increasing the substrate temperature, and the extinction coefficient of the films in the visible region is in the order of 10−3, indicating low optical loss. The nanomechanical properties of the films were investigated using nanoindentation technique. Young’s modulus and hardness for all films are found to be increased with the increase of substrate temperature.