High-speed solar-blind UV photodetectors using high-Al content Al0.64Ga0.36N/Al0.34Ga0.66N multiple quantum wells

We demonstrate high-external quantum efficiency (similar to 50%) solar-blind AlGaN p-n junction photodetectors with high-Al content multiple quantum wells (MQWs). A peak responsivity of 0.1A/W at 250 nm, which falls >10(3) by 280 nm, indicates that the optical absorption is dominated by the MQW structures. At a reverse bias of 0.5V, the dark current is <0.1 pA. The readout RC-limited time response is measured as 0.4 mu s, and an achievable detector RC-limited time response of 2 ns is estimated. The devices do not show internal gain, which accounts for their high speed. (C) 2017 The Japan Society of Applied Physics