DD1, Ultraviolet Photodetectors with Novel Oxide Thin Films: Shizuo

A variety of wide band gap oxide semiconductors, which are recognized as stable and environmental-friendly materials, can meet various demands for detectable wavelength, sensitivity, cost, and endurance of ultraviolet photodetectors, in contrast to III-nitride semiconductors which always needs high-cost and dangerous sources for their growth. In this presentation, we report several oxide semiconductors we have developed as the materials for ultraviolet photodetectors. Ga2O3 possesses large band gap of 4.8 eV (258 nm), which is suitable for UV-C photodetectors. HIgh quality Ga2O3 substrates allow the Schottky-type photodetectors using high-resistive layers formed on the substrates by thermal annealing in oxygen atmosphere. The photodetector exhibited the photoresponsivity of 0.037 A/W at 250 nm with the external quantum efficiency of 18 %. The photodetector was capable of detecting solar-blind light of as weak as 1 nW/cm2 from the flame in normal room lighting. Robust properties of Ga2O3 against defect generation have allowed hundred-hours operation without noticeable degradation as a power monitor for a low-pressure mercury lam