Band alignment of ultrawide bandgap ε-Ga₂O₃/h-BCN heterojunction epitaxially grown by metalorganic chemical vapor deposition

In this work, ultrawide bandgap ɛ-Ga₂O₃/h-BCN heterojunctions were epitaxially grown on sapphire substrates by metalorganic chemical vapor deposition (MOCVD). This heterojunction was systematically studied by various material characterization techniques, including X-ray diffraction (XRD), atomic force microscope (AFM), transmission electron microscopy (TEM), high-resolution X-ray photoelectron spectroscopy (HR-XPS), energy dispersive spectroscopy (EDS), and UV–Vis-NIR spectroscopy. h-BCN conformed to a two-dimensional layered structure, while ɛ-Ga₂O₃ grown on h-BCN was found to be polycrystalline. TEM and EDS element mapping showed a clear and sharp interface of the heterojunction. HR-XPS measurements were carried out to unveil the band alignment of the ε-Ga₂O₃/h-BCN heterojunction. It was found that the ε-Ga₂O₃/h-BCN heterojunction exhibits a type-II band alignment with a conduction band offset of 2.77 eV and a valence band offset of − 1.60 eV. This work provides valuable information on the epitaxial growth and band alignment of the ultrawide bandgap ɛ-Ga₂O₃/h-BCN heterojunctions, opening the door to a myriad of electronic and photonic applications.