Band Alignment at the Al_2O_3/\beta-Ga_2O_3 Interface with CHF_3 Treatment

The energy band alignment at the atomic layer deposited Al_2O_3/\beta-Ga_2O_3 interface with CHF_3 treatment was characterized by x-ray photoelectron spectroscopy and secondary ion mass spectrometry (SIMS). With additional CHF_3 plasma treatment, the conduction band offset increases from 1.95\pm0.1 eV to 2.32\pm0.1 eV; and the valence band offset decreases from 0.21\pm0.1 eV to -0.16\pm0.1 eV. As a result, the energy band alignment changes from type I to type II. This energy band alignment transition could be attributed to the downshift of the core-level of Ga 3d, resulting from the Ga–F bond formation in the F-rich interfacial layer, which is confirmed by the SIMS results.