Ir/n-ZnO Schottky Barrier Ultraviolet Photodiodes

ZnO Schottky barrier photodiodes (PDs) with Iridium (Ir) contact electrodes were fabricated in this study. We could reduce the reverse leakage current and improve the performance of ZnO ultraviolet (UV) PDs by using 500
^°
C, O
₂
annealing. This could be attributed to the formation of IrO
₂
after thermal annealing. With -1 V applied bias, it was found that the reverse current for nonannealed and 500
^°
C, O
₂
annealed PDs were 4.46 × 10
^{- 9}
and 8.87 × 10
^-11
A, respectively. It was also found that we could enhance UV-to-visible rejection ratio, reduce noise level, and enhance the detectivity by high-temperature oxygen annealing.