GaN Schottky photodiodes with annealed Ir/Pt semi-transparent contacts

We have fabricated the Schottky photodiodes on GaN epitaxial wafer by using Ir/Pt contact. It was found that the transmittance of Ir/Pt film increased while the dark current became significantly smaller after annealing. The leakage current after annealing in O2 was shown to be about four orders of magnitude smaller than that without annealing. With a − 6 V applied bias, it was found that the photocurrent to dark current contrast ratio and the maximum responsivity were 4.03 × 104 and 0.189 A/W for photodiodes after annealing at 600 °C.