Improved Performances of InGaN Schottky Photodetectors by Inducing a Thin Insulator Layer and Mesa Process

The performances of InGaN Schottky photodetectors with varied fabrication processes were investigated. The photoresponse and dark current of InGaN Schottky photodetectors can be obviously improved by inserting a thin Si3N4 passivation layer between the InGaN layer and the Schottky metal. Furthermore, a mesa process gives not only a further increase in the photoresponse but also a pronounced reduction in the reverse leakage current of about two orders of magnitude. A lateral surface leakage current mechanism associated with the 2-D variable-range hopping conduction through high-density surface states in InGaN is proposed to explain the reduction of the reverse leakage current after etching the mesa.