Improved performance of GaN-based Schottky barrier photodetectors by annealing Ir/Pt Schottky contact in O₂

Nitride-based UV Schottky barrier photodetectors (PDs) with Ir/Pt after annealing in O₂ at 600 °C were fabricated successfully. With -5 V applied bias, the reverse leakage current of the annealed PD was 3.65 × 10^-12 A. It was found that we could achieve the larger Schottky barrier height, the smaller dark current and the larger photocurrent to dark current contrast ratio by annealing Ir/Pt. After annealing, the Schottky barrier height increased from 0.91 eV to 1.03 eV and the ideality factor decreased from 1.58 to 1.16. Such a result indicated that the dominant current transport mechanism may be thermionic emission and the Schottky contact is near-ideal after annealing. These results could be attributed to the formation of IrO _x phase. It was also found that responsivity and the UV-to-visible rejection ratio were 0.19 A/W and 1.05 × 10³ after annealing with -6 V applied bias.