Band alignments of SiO2 and HfO2 dielectrics with (AlxGa1-x)2O3 film (0≤x≤0.53) grown on Ga2O3 buffer layer on sapphire

We report the band alignment of SiO2 and HfO2 with (AlxGa1-x)2O3 (0 ≤ x ≤ 0.53) film utilizing the high resolution X-ray photoelectron spectroscopy (XPS) measurements. (AlxGa1-x)2O3 film were epitaxially grown on sapphire with Ga2O3 buffer layer. The crystal quality and orientation of (AlxGa1-x)2O3 (0 ≤ x ≤ 0.53) samples were firstly studied with high-resolution X-ray diffraction (HRXRD). Ga 2p, Si 2p, Hf 4f and valence band spectra were used to determine the band alignment. As the Al mole fraction x increases from 0 to 0.53, conduction band alignments of SiO2/(AlxGa1-x)2O3 and HfO2/(AlxGa1-x)2O3 increase from 1.9 to 2.6 eV and from 1.1 to 2.0 eV, with the valence band alignment decrease from 1.9 to 0.6 eV and from −0.2 to −1.7 eV, respectively. From the results that wider bandgap with a larger conduction band alignment, reflects that Ga2O3 and (AlxGa1-x)2O3 is a promising candidate for power devices.