A Back-Illuminated Vertical-Structure Ultraviolet Photodetector Based on an RF-Sputtered ZnO Film

A back-illuminated vertical-structure ZnO ultraviolet (UV) detector was fabricated using an indium-tin oxide (ITO) electrode. Ordered ITO and ZnO films were grown on a quartz substrate by radiofrequency sputtering. At 5 V bias, the dark current was 640 mu A and the photocurrent was 16.8 mA under UV illumination (365 nm, 10 mu W), indicating a high responsivity of 1616 A/W. The response time measurements showed a rise time of 71.2 ns and a decay time of 377 mu s. The ZnO detector performed well and can be used in a focal-plane array for UV image detection.