Regensburg 2025 – scientific programme
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O: Fachverband Oberflächenphysik
O 86: Electronic Structure of Surfaces: Spectroscopy, Surface States II
O 86.8: Talk
Thursday, March 20, 2025, 16:45–17:00, H2
Composition and band gap of aluminum alloyed beta-gallium oxide determined by XPS — •Lukas Schewe1, Jana Rehm2, Ming-Chao Kao3, Vedran Vonk3, Zbigniew Galazka2, Saud Bin Anooz2, Andreas Popp2, and Jan Ingo Flege1 — 1Fachgebiet Angewandte Physik und Halbleiterspektroskopie, BTU Cottbus-Senftenberg — 2Leibnitz-Institut für Kristallzüchtung, Berlin — 3CXNS-Center for X-ray and Nano Science, DESY Hamburg
Beta-phase gallium oxide is a wide-gap semiconductor with a band gap of 4.85eV
and promising prospects in high-power electronics. The electric breakdown field can be increased by alloying the oxide with aluminum, further enhancing its properties.
The present work discusses structural and electronic properties of β-(AlxGa1−x)2O3 thin films and bulk crystals with Al content of up to 33 %. Their Al content was determined by X-ray photo-electron spectroscopy (XPS) and compared to the values estimated from X-ray diffraction (XRD) and inductively coupled plasma optical emission spectroscopy (ICP-OES). Additionally, the thin films have been investigated by XPS depth profiling, i.e., XPS combined by sequential Ar+ sputtering, revealing lower aluminum content at the sample surface, which points to possible surface segregation of gallium during annealing. Furthermore, the band gap was determined by electron loss spectra from XPS and optical absorbance measurements and correlated to the Al content estimated for both thin films and bulk crystals.
Keywords: high power electronics; beta aluminum gallium oxide; epitaxy; bandgap; XPS