High-performance solar-blind Al_(0.6)Ga_(0.4)N/Al_(0.5)Ga_(0.5)N MSM type photodetector

摘要

An Al_(0.6)Ga_(0.4)N/Al_(0.5)Ga_(0.5)N 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 Al_(0.6)Ga_(0.4)N/Al_(0.5)Ga_(0.5)N 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 μW/cm~2, an extremely low dark current (10~(-11)A) and high photocurrent (5 × 10~(-5)A) were achieved at a bias voltage of 5 V. 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.