TiO2 ultraviolet detector based on LaAlO3 substrate with low dark current

In this letter, metal-semiconductor-metal (MSM) ultraviolet TiO2 photodetectors based on LaAlO3 substrate were fabricated. TiO2 nano-film was prepared via a sol-gel method, and then was spin-coated on single crystal LaAlO3 substrate. Pt interdigitated electrodes were deposited on the top of TiO2 film. At 5 V bias, the dark current of the detector was only 50 pA, which is much lower than TiO2-based detector. When irradiated by 270 nm UV light, a high photoresponse of the device was obtained. The ratio of photocurrent to dark current was nearly 5 orders, which is much higher than other photodetectors based on TiO2 reported. The rise and fall time of the detector were 550 ms and 380 ms, respectively. The very low dark current and high sensitivity demonstrate the excellent application of the device in UV photoelectric detection.