ウルツ鉱型半導体の力学特性に及ぼす光環境効果の実験的計測とメカニズム解明

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This project aims to elucidate how light affects the mechanical properties of wurtzite semiconductors. Many advanced semiconductor compounds, such as GaN and ZnO, possess wurtzite structure, which consists of two individual hexagonal close-packed sublattices. In FY2022, our studies mainly focused on wurtzite ZnO, a representative third-generation semiconductor material. Photoindentation technique, i.e., in-situ nanoindentation experiments with a controllable light illumination system, was adopted to evaluate the mechanical responses at the nanoscale under different light conditions. Three types of photoindentation experiments were applied on two ZnO single crystals with different orientations. Low-load indentation pop-in tests were performed to investigate the light effects on dislocation nucleation. Middle-load quasi-indentation tests were conducted to verify the photo-hardening effects of different orientations. High-load indentation creep tests were carried out to study the influence of light on dislocation multiplication and motion along different slip planes. It was found that light only shows a slight influence on the dislocation nucleation event, but significantly affects dislocation motion.