High-Performance Ultraviolet Photodetector Based on Polycrystalline ${\rm SrTiO}_{3}$ Thin Film

SrTiO₃ (STO) thin film has been fabricated on fused-quartz wafer by radio-frequency magnetron sputtering. The Ag interdigited electrodes were then evaporated on STO thin film in order to form the metal-insulator-metal photoconductive detector. Our photodetector exhibits a high photoresponse in the range of 225-340 nm with an ultraviolet-visible rejection ratio (R310 nm/R400 nm) of two orders of magnitude, indicating an intrinsic characteristic of visible-blindness. The maximum photocurrent responsivity is about 105 mA/W measured at 310 nm and the corresponding quantum efficiency is 42.1%. The dark current is only 0.4 nA at 50 V bias. Furthermore, the STO thin film detector presents a transient photovoltaic signal with a rise time of ~330 ps and a fall time of ~480 ps under the excitation of a 355-nm-pulsed laser, suggesting an ultrafast response characteristic of our STO thin film detector.