Middle-ultraviolet-enhanced photodetectors based on Mg_(0.4)Zn_(0.6)O/ZnO homo junction with a high selectivity for 300 nm around light

摘要

High-quality Mg_(0.4)Zn_(0.6)O film with a ZnO buffer layer was prepared on glass by the reactive magnetron cosputtering method, and the MgZnO/ZnO homojunctions were fabricated into metal-semiconductor-metal middle ultraviolet (UV) photodetectors (PDs). The MgZnO-based PD with a ZnO buffer layer showed a high selectivity for 300 nm around middle UV light and its responsivity was larger than that of the PD without a buffer layer. Its peak responsivity was 0.45 A W~' at 300 nm under —5 V bias, which was comparable to the highest value ever reported in MgZnO-based PDs. Also, we observed that the PDs with a smaller spacing of the finger electrodes showed a larger responsivity, indicating that the PD with a small spacing shows a large internal gain. The results may provide a simple route to gain low-cost and high-performance middle UV PDs.