Microstructure, wettability and electrical properties of n-ZnO/ZnO-SL/p-CuO heterojunction.

ZnO/ZnO-SL/CuO heterojunction was successfully fabricated on Cu foil by hydrothermal and sol-gel method. Crystalline phase, surface morphology and photoluminescence spectrum of the heterojunction were measured by X-ray diffraction, scanning electronic microscopy and fluorescence spectrometer, respectively. Contact angles of ZnO thin films were measured using a contact angle apparatus. The current-voltage characteristics of heterojunction in dark were investigated at room temperature. The results indicated that the heterojunction was composed of CuO phase and ZnO phase. The post-heat temperature of 250 °C was beneficial to preferred growth of ZnO thin film along the c-axis direction. The Sample 2 was composed of the uniform, compact and vertically aligned ZnO nanorods and has the most obvious hydrophobic-to-hydrophilic transition. The transport characteristics of the Sample 2 may be related to the space-charge-limited current in region II and a trapped-charge-limited current in region III. [ABSTRACT FROM AUTHOR]