High-performance solar-blind Al0.6Ga0.4N/Al0.5Ga0.5N MSM type photodetector

An Al0.6Ga0.4N/Al0.5Ga0.5N metal-semiconductor-metal (MSM) deep-ultraviolet (DUV) photodetector was developed. It possesses both high photosensitivity and high rejection ratios in comparison to photomultiplier tubes (PMTs). The photodetector was designed to have a two-dimensional electron gas layer at the Al0.6Ga0.4N/Al0.5Ga0.5N hetero-interface, which plays an important role in increasing the photosensitivity. Additionally, for reducing the dark current, a V/Al/Mo/Au electrode was employed as a Schottky electrode with an appropriate barrier height. Upon irradiation with 10 mu W/cm(2), an extremely low dark current (10(-11) A) and high photocurrent (5 x 10(-5) A) were achieved at a bias voltage of 5V. The photodetector was true solar-blind with a cut-off wavelength of 280 nm. A high photosensitivity of 10(6) A/W and a rejection ratio of 10(6) were realized under the irradiation of 10 nW/cm(2) DUV photons. The present results revealed that the AlGaN/AlGaN MSM DUV photodetector is one of the most suitable candidates for an all solid-state photodetector with a performance superior to PMTs. Published by AIP Publishing.