AlGaN solar-blind Schottky photodiodes fabricated on 4H-SiC

Solar-blind AlGaN-based Schottky photodiodes grown on 4H-SiC substrate are reported. The fabricated devices demonstrate dark current density as low as 2.2/spl times/10/sup -10/ A/cm/sup 2/ at a reverse bias of 5 V. A zero-bias peak responsivity of 44 mA/W was achieved at 256 nm, corresponding to an external quantum efficiency of 21%. Under a low illumination power density of 10 nW/cm/sup 2/, a rejection ratio of more than two orders of magnitude was observed in the wavelength range from 270 to 310 nm. A room-temperature solar-blind detectivity of 7.9/spl times/10/sup 14/ cm/spl middot/Hz/sup 1/2/W/sup -1/ was estimated at 256 nm under zero bias.