Continuous real-time O 1s core XPS spectra of initial O2 molecule adsorption on polar and m-plane surfaces of GaN

The initial adsorption behavior of different GaN surfaces (the polar Ga-face (+c) and N-face (−c) and the nonpolar (101̅0) (m)-plane) under O2 molecule beam irradiation was studied by continuous real-time monitoring of the O 1s core X-ray photoelectron spectra generated under synchrotron radiation. XPS measurements were performed at BL23SU, SPring-8. Analyzing the chemical shift allows for determining which site the oxygen atom bonds to depending on the polarity and plane of GaN, which contributes to detailed understanding of the surface oxidation process. The first column of each scan is the kinetic energy, and the second column is the count rate. Before starting XPS analysis, the sample was annealed at 900 °C for 20 minutes. A scan was obtained every 30 seconds while irradiating the surface with O2 molecule beam. The data are in CSV and VAMAS formats.