Solution growth of crystalline ZnO thin film and its photodetector application

Highlights: • Synthesis diversity structures of ZnO materials by hydrothermal solution method at low temperature. • Surface morphology of ZnO material depends on the concentration of Cu(NO₃)₂. • ZnO crystalline thin film with smooth surface has been obtained. • Metal-semiconductor-metal structure photo detector based on ZnO thin films with the high performance. We describe synthesis of high-quality crystalline ZnO thin films via hydrothermal solution method at low temperature. A variety of ZnO material structures (nanowires, nanorods, and thin films) have been obtained with various Cu(NO₃)₂ concentrations of the precursor solution. Interdigitated finger metal-semiconductor-metal structure UV photodetector with gold Schottky contact is fabricated based on the ZnO materials, which has been employed to investigate the UV photo detection performance. Our results indicate that the performance of the device depends on the structure of the ZnO materials. With Cu(NO₃)₂ concentration of 0.25 mM, the photodetector with the lowest dark current of 1.88 nA, responsivity of 1.46A/W, and UV-to-Visible rejection ratio up to four orders at 1 V bias has been achieved.