Exploration of novel materials for photochemical water splitting based on semiconductor nanowires and nanostructures

为了探索新型的光化学水裂解材料，我们尝试了GaN基纳米结构的制备及其电化学性能的表征。GaN和InGaN纳米结构的生长尝试通过使用RF等离子体辅助分子束外延的选择性区域生长。成功地制备了GaN的六角锥形结构，并建议使用交替掩模材料进行选择性区域生长，以实现适合于水裂解的纳米线。我们还通过测量GaN在电介质中有光照射和无光照射时的电流-电压特性，研究了GaN的光电化学性质。此外，还将它们的特性与光辅助化学刻蚀制备的表面具有高密度纳米孔的多孔结构进行了比较，发现多孔结构比平面结构允许更大的光电流。

To explore novel materials for photochemical water splitting, we attempted the fabrication of GaN-based nanostructuers and their characterization of electrochemical properties. Growth of GaN and InGaN nanostructures were attempted by selective-area growth using RF-plasma-assisted molecular beam epitaxy. Hexagonal pyramidal structures of GaN were successfully fabricated and a use of alternate mask material for selective-area growth was suggested to be important to realized nanowires which is suitable for water splitting. We also investigated the photo-electrochemical properties of GaN by measureing current-voltage characteristics of GaN in electroryte with and without light irradiation. Furthermore, their characteristics was compared with porous structures, which were fabricated by photo-assisted chemial etching and had high-denstiy nanometer-sized pores on the surface, and it was found that porous structures allowed much lager photocurrent as compared to planar structures.