Effects of depositing temperature on structural, optical and laser-induced damage properties of Ga2O3 films deposited by electronic beam evaporation

Abstract

Ga2O3 thin films were prepared by electron-beam evaporation from a starting material of high-purity Ga2O3 granules. The relations between depositing temperature and properties including structural and optical aspects of the film were investigated. When the depositing temperatures were 50, 100, 150 and 200 °C, the corresponding refractive indexes were 1.790, 1.799, 1.816 and 1.830 at a wavelength of 532 nm. With the rise of depositing temperature, transparency of the thin films presented a decreasing trend in the ultraviolet as well as visible regions, and the edges of absorption showed red-shifted characteristic simultaneously. During the testing process, a 532 nm laser with variable energy from 5 to 200 mJ was loaded on film for 10 ns. The laser-induced damage threshold (LIDT) of the Ga2O3 samples rose up from 1.89, 3.28, and 4.13 to 4.49 J/cm2 against the increasing of depositing temperature. It demonstrated that optical properties of Ga2O3 film relied heavily on the depositing temperature.