GaN/InGaN avalanche phototransistors

We report on III-nitride (III-N) avalanche phototransistor (APT) action by illuminating ultraviolet (UV) photons onto a GaN/InGaN npn heterojunction bipolar transistor in an open-base configuration. A high responsivity of >1A/W was measured for the device operating at a collector-to-emitter voltage (V-CE) of <15V in the phototransistor mode. The carrier multiplication in the reversed biased collector leads to a photocurrent avalanche as V-CE increases. At lambda = 380 nm, the GaN/InGaN APT shows a responsivity of >68A/W at V-CE = 95V. The InGaN APT demonstrates the feasibility of using III-N bipolar transistor structures for high-sensitivity UV photodetection applications. (C) 2015 The Japan Society of Applied Physics