Figure 2

Core levels and VBE spectra. (a) Core level of N1s recorded in a 6-μm-thick GaN film. (b) The VBE spectra from the 6-μm-thick GaN film. (c) Core level of O1s recorded in a 200-nm-thick Ga₂O₃ film. (d) The VBE spectra of the 200-nm-thick Ga₂O₃ film. (e) Core level of N1s recorded on the Ga₂O₃/GaN heterostructure sample. (f) Core level of O1s recorded on the Ga₂O₃/GaN heterostructure sample. (g) Core level of Ga3d recorded on the Ga₂O₃/GaN heterostructure sample. (h) Core level of Ga3d recorded in a 6-μm-thick GaN film. (i) Core level of O1s recorded in a 200-nm-thick Ga₂O₃ film.