Epitaxial growth and determination of the band alignment for NixMg1-xO/MgO interface by laser molecular beam epitaxy

Abstract

By laser molecular beam epitaxy, single crystalline NixMg1-xO films have been successfully synthesized on MgO(100) surface. The in situ reflection high-energy electron diffraction patterns show that the induced O2 background gas with at least 1.0 × 10−3 Pa is necessary to the epitaxial growth of NixMg1-xO films. The X-ray diffraction patterns reveal the single-phase growth along (200) direction. The energy band alignment at the interface is investigated by employing in situ X-ray photoelectron spectroscopy. The valence band offsets are determined to be from 1.47 eV to 1.50 eV with the decrease of Ni content (0.39 → 0.35). Furthermore, the work function is evaluated by using in situ ultraviolet photoemission spectroscopy, indicating the values from 4.33 eV to 4.64 eV. This study provides a promising guidance for the solar-blind device design and fabrication.