XPS spectral analysis of the (010) surface of bulk Sn-doped β-Ga2O3 single crystals

The surface chemistry of a (010)-oriented β-Ga2O3 (beta-gallium oxide) single crystal was investigated using x-ray photoelectron spectroscopy (XPS). A 2 in. wafer was sectioned into 5 × 5 mm2 specimens, and both ex situ and in situ surface cleaning procedures were incorporated to minimize contamination prior to analysis. XPS measurements included a wide energy survey and high-resolution scans of Ga 2p, Ga 3s, Ga 3p, Ga 3d, O 1s, and C 1s core levels, as well as the valence band region and Ga LMM and O KLL x-ray induced Auger electron spectroscopy (XAES) transitions. The spectra consistently revealed Ga3+ as the only oxidation state, in agreement with the expected chemical state for β-Ga2O3. Additionally, the composition derived from the quantitative analysis indicates the existence of stoichiometric Ga2O3. Carbon was present only at trace levels, reflecting an effectively cleaned surface. The Auger transitions of Ga and O provided complementary confirmation of oxidation states and contributed to a more comprehensive understanding of the surface electronic structure.