Dual-wavelength ultraviolet photodetector based on vertical (Al,Ga)N nanowires and graphene* *Project supported by the National Key Research and Development Program of China (Grant No. 2018YFB0406602), Natural Science Foundation of Jiangsu Province, China (Grant No. BK20180252), Key Research Program of Frontier Sciences, CAS (Grant No. ZDBS-LY-JSC034), the National Natural Science Foundation of China (Grant Nos. 61804163, 61875224, and 61827823), the Key

Abstract

Due to the wide application of UV-A (320 nm–400 nm) and UV-C (200 nm–280 nm) photodetectors, dual-wavelength (UV-A/UV-C) photodetectors are promising for future markets. A dual-wavelength UV photodetector based on vertical (Al,Ga)N nanowires and graphene has been demonstrated successfully, in which graphene is used as a transparent electrode. Both UV-A and UV-C responses can be clearly detected by the device, and the rejection ratio (R 254 nm/R 450 nm) exceeds 35 times at an applied bias of –2 V. The short response time of the device is less than 20 ms. Furthermore, the underlying mechanism of double ultraviolet responses has also been analyzed systematically. The dual-wavelength detections could mainly result from the appropriate ratio of the thicknesses and the enough energy band difference of (Al,Ga)N and GaN sections.