GaN-based ultraviolet p-i-n photodiodes with buried p-layer structure grown by MOVPE

The following study presents an analysis of AlGaNGaN p-i-n photodiode, which was designed with a buried p+ -GaN layer combining a heavy doped n++ - In0.3 Ga0.7 N layer in order to form a p+ n++ tunneling junction under the AlGaNGaN n-i-p heterostructure. Compared to the conventional AlGaN -based p-i-n photodiodes, the inverted devices are capable of low-resistivity and high aluminum-containing n-type AlGaN top contact layer. The inverted devices exhibited a typical unbiased peak responsivity of 0.1 AW at 350 nm corresponding to a quantum efficiency of around 35%. The unbiased rejection ratio was about four orders of magnitude over the ultraviolet and visible regions of the spectrum. The typical dark current density of the inverted devices was below 5 nA cm2 at the reverse bias below 2 V.