Preparation of High Al Content (AlxGa1-x)2O3 Films by Low-Pressure Reactive Vapor Deposition on Sapphire Substrates

Beta-(AlxGa1-x)(2)O-3 thin films were prepared on c-plane sapphire substrates by low-pressure reactive vapor deposition at different temperature. The crystal structure, surface morphology, and optical properties of beta-(AlxGa1-x)(2)O-3 films were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscope (AFM), X-ray photoelectron spectroscopy (XPS), and transmission spectra. The beta-(AlxGa1-x)(2)O-3 films were preferred [(2) over bar 01] orientation. The film grown at 1400 degrees C has narrower full width half maximum (FWHM) than grown at 1450 degrees C. As the growth temperature increases, the Al group decreases. The Al content of beta-(AlxGa1-x)(2)O-3 films grown at 1400 degrees C and 1450 degrees C are x = 0.524 and x = 0.489, respectively. The SEM and AFM images showed different growth mode for beta-(AlxGa1-x)(2)O-3 films grown at 1400 degrees C and 1450 degrees C and their root-mean-square roughness (RMS) values are 5.27 nm and 5.33 nm, respectively. All the prepared beta-(AlxGa1-x)(2)O-3 films have high transmittances exceeding 90% in visible region and large optical bandgap above 6 eV. These results indicate that low-pressure reactive vapor deposition technology is a promising growth technology for a high quality beta-(AlGa)(2)O-3 films with tunable properties. (C) 2020 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited.