Unintentionally doped AlGaN thin films are grown on c-plane(0001)sapphire substrate by metal-organic chemical vapor deposition,and low-temperature AlN is deposited onto sapphire substrate used as a bu?er layer.AlGaN metal-semiconductor-metal ultraviolet photodetectors with Ni/Au interdigitated contact electrodes are then fabricated by lift-off technology.The dark current of the AlGaN photodetectors is5.61×10-9A at 2-V applied bias and the peak response occurrs at 294 nm. Unintentionally doped AlGaN thin films are grown on c-plane (0001) sapphire substrate by metal-organic chemical vapor deposition, and low-temperature AlN is deposited onto sapphire substrate used as a bu er layer. AlGaN metal-semiconductor-metal ultraviolet photodetectors with Ni / Au interdigitated contact electrodes are then fabricated by lift-off technology. The dark current of the AlGaN photodetectors is 5.61 × 10 -9 A at 2-V applied bias and the peak response occurrs at 294 nm.