Crystallinity of GaN thin films directly grown on metal foils by the reactive evaporation method

GaN thin films are grown on several metal foils of 50 mum thickness and the ir crystallinity is compared with that of films on a quartz glass substrate . X-ray diffraction peaks other than the GaN c-face appear when the metal f oils are used, while highly c-axis-oriented GaN thin films are obtained on the quartz glass substrate under the same growth conditions. The reasons fo r the difference in their crystallinity are discussed from the viewpoints o f surface roughness, diffusion property and crystallinity of the metal foil s used.