Daishi Shiojiri

Influence of Rapid Thermal Annealing and Substrate Terrace Width on Self-Organizing Formation of Periodic Straight Nanogroove Array on NiO(111) Epitaxial Thin Film

Room-temperature-grown NiO(111) epitaxial thin films on atomically stepped sapphire (0001) substrates by pulsed laser deposition have straight atomic steps. For a terrace width of about 50 nm, a periodic straight nanogroove array with a depth of about 6 nm was formed over the film surface after rapid thermal annealing. When using a substrate with a terrace width of about 250 nm, it is observed that two types of 180°-rotated triangular crystalline domain are alternately grown on each film terrace divided by the nanogrooves.

Room-temperature laser annealing for solid-phase epitaxial crystallization of .BETA.-Ga2O3 thin films

The epitaxial crystallization of β-Ga2O3 thin films on NiO-buffered α-Al2O3(0001) substrates via the solid-phase crystallization of amorphous Ga2O3 thin films by KrF excimer laser annealing at room temperature (RT) was examined. The results of X-ray and reflection high-energy electron diffraction measurements indicated that the epitaxial β-Ga2O3 thin films were fabricated by RT laser annealing. The optical bandgap of the thin films was estimated to be 4.9 eV from the results of UV/vis transmittance measurements. In the cathodoluminescence spectrum, UV–green luminescence was observed for the thin films. These optical properties are similar to those of bulk β-Ga2O3.