High-performance visible-blind GaN-based p-i-n photodetectors

We report high performance visible-blind GaN-based p-i-n photodetectors grown by metal-organic chemical vapor deposition on c-plane sapphire substrates. The dark current of the 200μm diameter devices was measured to be lower than 20pA for bias voltages up to 5V. The breakdown voltages were higher than 120V. The responsivity of the photodetectors was ∼0.23A∕W at 356nm under 5V bias. The ultraviolet-visible rejection ratio was 6.7×103 for wavelengths longer than 400nm.