Low-Temperature Selective Growth of Heteroepitaxial α-Al2O3 Thin Films on a NiO Layer by the Electron-Beam Assisted PLD Process

Abstract

AbstractSelective heteroepitaxial growth of α-Al2O3 thin films on a NiO layer was investigated using an electron-beam assisted pulsed laser deposition process. The epitaxial NiO layer was grown on an ultrasmooth sapphire (α-Al2O3 single crystal) (0001) substrate. The α-Al2O3 thin film could be grown epitaxially only in the electron-beam irradiated region of the epitaxial NiO layer at 300°C, while the amorphous Al2O3 film was grown in the non-irradiated region. The homoepitaxial growth of α-Al2O3 thin films could not be attained on the sapphire (0001) substrate at 300°C. This indicates that the electron-beam irradiation enhances heteroepitaxial growth of the α-Al2O3 thin films on the NiO layer at 300°C. When we annealed the epitaxial Al2O3/NiO bilayer film at 350°C in a hydrogen atmosphere, we could reduce only the NiO layer to an epitaxial Ni metal layer, allowing the fabrication of epitaxial Al2O3/Ni (insulator/metal structure) films. The fabricated Al2O3/Ni bilayer films exhibited a very smooth surface.