Solar-blind photodetector based on LaAlO3 with low dark current.

In this letter, metal-semiconductor-metal (MSM) solar-blind photodetector was fabricated on LaAlO3 (110) substrates with Pt and Au electrodes. The substrate material was characterized by XRD and UV-visible absorption spectrum. At 10 V bias, the photodetector with Pt electrodes shows a very low dark current of 4.1 pA, which is much smaller than that of detector with Au electrodes (14.6 pA). The low dark current may be attributed to the high density steps and facets on the (110) surface as well as the large lattice mismatch at the Pt/LaAlO3 interface. The device exhibits a peak responsivity of 32.5 mA/W at 200 nm ultraviolet light, which lies in the solar-blind spectral region (200-280 nm). The reasons of low dark current and high responsivity, which were important to photodetectors, were discussed in detail.