Abstract
In this article, we determine the band alignment at the thermodynamically stable heterointerface between a ((2) over bar 01)-oriented single-domain beta-(In0.072Ga0.928)(2)O-3 crystal and bulk c-plane sapphire, namely, (0001)-oriented alpha-Al2O3. The beta-(In0.072Ga0.928)(2)O-3 layer was deposited on the bulk sapphire crystal using pulsed laser deposition. The beta-(In0.072Ga0.928)(2)O-3 and alpha-Al2O3 valence and conduction band offsets (VBO and CBO, respectively) were found to be 0 +/- 0.1 and 4.87 +/- 0.1 eV, respectively. Accordingly, we identified a type-I alpha-Al2O3/beta-(In0.072Ga0.928)(2)O-3 heterojunction. X-ray diffraction measurements confirmed ((2) over bar 01)-oriented single-domain beta-(In0.072Ga0.928)(2)O-3 high-quality films with in-plane rotations of every 120 degrees, whereas Rutherford backscattering spectrometry was employed to verify the bulk composition. We employed high-resolution X-ray photoelectron spectroscopy to measure the core level binding energies of Al 2p and Ga 2p 3/2 with respect to the valence band maxima of the beta-(In0.072Ga0.928)(2)O-3 and alpha-Al2O3 layers, respectively. Then, we measured the energy separation between the Al 2p and Ga 2p3p core levels at the interface of the heterojunction. beta-(InGa)(2)O-3 is a wide-bandgap semiconductor, while alpha-Al2O3 is a well-known dielectric. Together, they can be employed to fabricate reliable and efficient power electronic devices. We also combined high-resolution transmission electron microscopy, X-ray diffraction, and fast Fourier transform algorithms to characterize the dislocations at the interface. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement