Heteroepitaxial β-Ga2O3 thick films on sapphire substrate by carbothermal reduction rapid growth method

Abstract

The heteroepitaxial β-Ga2O3 thick films were rapidly grown on various oriented sapphire substrates using carbothermal reduction method. The β-Ga2O3 films were prepared in our home-made vertical dual temperature zone furnace. The growth direction as well as surface morphology showed the strong dependence on the orientation of the sapphire substrate. The fastest growth rate was obtained reaching approximate 15 μm h−1 on c-plane sapphire substrate according to the average 30 μm thickness of β-Ga2O3 films grown for 2 h measured by cross-section scanning electron microscope. The Raman spectra indicated the pure-phase β-Ga2O3 films without obvious strain. The bandgap for grown films were in range of 4.6–4.7 eV confirmed by x-ray photoelectron spectra and Tauc plot from absorption spectra. Secondary ion mass spectrometry was used to check the impurities indicating a limited amount of residual carbon inside the films even though graphite as the reducing agent. The results in this work give promising alternative method of rapid epitaxial β-Ga2O3 thick films for the application on high-power electronic devices.