Ultraviolet photodetectors based on ZnO nanowires with SiO₂/ZnO multilayers

Ultraviolet photodetectors (UV PDs) have been a frequently studied focus of optoelectronic semiconductor devices because of their large range of applications. As one of the most famous materials in third-generation semiconductors, ZnO-based UV PDs have received a great deal of attention in various research areas. Due to the carrier transport channel and higher exciton bond energy, ZnO nanowires (NWs) have better photoelectron sensitivity under UV light than ZnO films. Here, well-organized ZnO NWs were fabricated on ZnO-seeded substrates via a hydrothermal method. Multilayers of double SiO 2 /ZnO(S/Z) layers were designed on the NWs, and the Schottky barrier was introduced by the close contact of the ZnO NWs and gold electrodes to improve the performance of ZnO UV PDs. Characteristics of the dark current, photocurrent, rise time, decay time, photo-to-current ratio (S), and responsivity values (Rs) of the PDs were studied. Furthermore, multilayer UV PDs were achieved on both Si and quartz substrates. S of the ZnO S/Z-based UV PDs fabricated on a silica substrate can reach 55.57, which is better than the values of ZnO UV PDs reported previously. Compared with silica-based UV PDs with S/Z layers, quartz-based UV PDs with S/Z layers show a higher performance of Rs, which reach 12.62 A/W. ZnO NWs with multilayers and the Schottky contact between ZnO NWs and Au are promising candidates in high-sensitivity UV PDs.