Filter-free AlGaN Photodiode with High Quantum Efficiency for Partial Discharge Detection

Abstract

In this study, we developed filter-free AlGaN based PIN photodiodes for partial discharge detection that can detect ultraviolet emission with a wavelength between 230 nm and 270 nm. The PIN epitaxial structure consisted of a p-Al0.6Ga0.4N/i-Al 0.46Ga0.54N/n-Al0.6Ga0.4N heterostructure with pGaN/p-AlGaN grading layers on top for improved ohmic contact formation. The fabricated photodiode exhibited highly selective photoresponse characteristics from 230 nm to 270 nm without an external filter. A peak photoresponsivity of 125 mA/W and quantum efficiency of 60% were achieved at 245 nm for a photodiode with a window diameter of 250 mu m under zero bias condition where the dark current was only 1.3 x 10(-8) A/cm(2) . The proposed AlGaN PIN photodiode has the advantages of zero standby power and no need for an external filter.