Simulation of GaN/InGaN avalanche phototransistors

Physical simulation of a two-terminal typical avalanche phototransistor with a floating base (2T-APT) based on GaN/InGaN is reported. The simulated current characteristic is also compared with the experiment result. Under high voltages, the carriers multiply in the reverse-biased base-to-collector (BC) junction. To reduce the avalanche breakdown voltage, the doping concentration and the thickness of the base are discussed in detail. It is found that the lower voltage could be achieved by decreasing the doping concentration and the thickness of base. Those results could be explained theoretically by the electric field and the potential barrier in the emitter-to-base (EB) junction and the BC junction.