Numerical simulation on the dependence of photoresponse on the thickness of the charge layer for GaN SAM avalanche photodiodes

GaN avalanche photodiode (APD) has important application prospects in the field of solar-blind ultraviolet (UV) detections. The back-illuminated GaN-based detector has been widely studied due to the advantages such as easy integration with readout circuit. Numerical model of GaN APD is established. The influence of the key function layer (charge layer) thickness on the device response and response current is also studied. Besides, the ideal charge layer thickness with the highest response is calculated.