Structural properties of β-Ga2O3 formed by dry thermal oxidization process on GaN

Dry thermal oxidation of GaN thin films grown on Al2O3 (0001) has been performed at different temperatures. The oxidized samples were investigated through X-ray diffraction (XRD) and atomic force microscope (AFM). For samples oxidized at temperatures from 800 °C to 950 °C, XRD peaks from the (−201), (−402) and (−603) planes of β-Ga2O3 were observed, indicating that a β-Ga2O3 layer was formed on GaN epitaxially. The epitaxial relationships were determined to be β-Ga2O3(−201)||GaN(002) and an in-plane orientation of β-Ga2O3[010]||GaN[110]. When the oxidation temperature is increased further to 1000 °C, in addition to the peaks from the (−201), (−402) and (−603) planes, extra peaks corresponding to other planes appeared, indicating that the oxidized layer had deteriorated to polycrystalline Ga2O3.