Design and simulation of p+-p-n-n+ structured Wz-GaN RAPDs for UV Sensing

In this paper the authors have carried out simulation experiment to study the opto-electric properties of p+-p-n-n+ structured WurtziteGaN (Wz-GaN) Reach-Through Avalanche Photodiodes (RAPDs). The photo responsivity and optical gain of the device are obtained within the wavelength range of 300 to 450 nm using a novel modeling and simulation technique developed by the authors. Two optical illumination configurations of the device such as Top Mounted (TM) and Flip Chip (FC) are considered for the present study to investigate the opto-electric performance of the device separately due to electron dominated and hole dominated photocurrents respectively in the visible-blind Ultra-Violet (UV) spectrum. The results show that better opto-electric performance of Wz-GaN RAPDs can be achieved when the photocurrent is made hole dominated by allowing the UV light to be shined on the n+-layer instead of p+-layer of the device.