Enhanced performance of AlGaN solar-blind ultraviolet avalanche photodiodes through electric field optimization

A back-illuminated AlGaN separate absorption and multiplication (SAM) solar-blind ultraviolet (UV) avalanche photodiode (APD) with an enhanced electric field is designed in this work. For the designed APD, a polarization electric field aligned with the applied electric field can be introduced by reducing the Al content of the p-type layer and inserting a multiplication layer with low-Al-content. The calculation results show that the designed APD exhibits a 9.6 V reduction in breakdown voltage, a 29 % increase in avalanche gain, and a 32 % improvement in peak responsivity at the breakdown voltage compared to the conventional SAM APD. In order to maximize the responsivity, further parameter optimization of the multiplication and p-type layers of the designed APD is performed using the Jaya algorithm. The results show that compared to the conventional SAM APD, the peak responsivity at the avalanche breakdown voltage and avalanche gain of the optimized APD are improved by 103 % and 63 %, respectively.