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

The following study presents an analysis of AlGaN/GaN p-i-n photodiode, which was designed with a buried p(+)-GaN layer combining a heavy doped n(++)-In0.3Ga0.7N layer in order to form a p(+)/n(++) tunneling junction under the AlGaN/GaN 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 A/W 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/cm(2) at the reverse bias below 2 V. (c) 2007 The Electrochemical Society.