Effect of oxidation temperature on physical properties of thermally grown oxide on GaN in N2O ambient

Physical characterizations of thermally grown oxide on n-type GaN in N2O ambient have been performed. The present study carried out the test at different oxidation temperature (700–1000 °C) in order to investigate the effect of oxidation temperature on the thermal oxide. Fourier Transform infrared spectrometer, X-ray diffraction and X-ray photoelectron spectroscopy were employed to identify the oxide layer formed on top of the GaN. Based on the analysis, Ga2O3 and GaON compounds were found on the sample oxidized at 700–900 °C. However, at 1000 °C, non-stoichiometry GaxOy and/or GaxOyNz compounds were formed. Apart from that, atomic force microscope results indicated that protrusions of grains appeared on the surface after thermal oxidation. The surface roughness of the oxide layer was also found to be increased with temperature. Besides, cross-sectional energy filtered transmission electron microscopy image revealed that the thickness of the oxide layer was increased with oxidation temperature. Remarkably, the activation energy calculated from the Arrhenius plot was found to be 1.65 eV (159.22 kJ mol−1). -- Highlights: ► Native oxide has been thermally grown on GaN in N2O ambient. ► Stoichiometry Ga2O3 and GaON were identified on sample oxidized at 700–900 °C. ► Non-stoichiometry GaxOy and/or GaxOyNz were formed on sample oxidized at 1000 °C. ► Activation energy of oxide formation was 1.65 eV (159.22 kJ mol−1).