A self-powered and broadband UV PIN photodiode employing a NiOx layer and a β-Ga<sub>2</sub>O<sub>3</sub> heterojunction
Jose Manuel Taboada Vasquez, Aasim Ashai, Yi Lu, Vishal Khandelwal, Manoj K. Rajbhar, Mritunjay Kumar, Xiaohang Li, Biplab Sarkar
Abstract
Abstract Crucial commercial and space applications require the detection of broadband ultraviolet (UV) rays spanning from UV-A to UV-C. In this study, the authors demonstrate a broadband UV photodetector employing a p-type NiO x layer and an n-type β -Ga 2 O 3 heterostructure in PIN configuration for the first time. Simulations are conducted to optimize the doping concentration and thickness of the NiO x layer, ensuring that (a) a reasonable depletion width is maintained within the NiO x layer for UV-A and UV-B light absorption; (b) anode ohmic contacts are formed on the nondepleted NiOx film, and (c) >70% of the UV-C light is absorbed by β -Ga 2 O 3 . The optimized NiO x / β -Ga 2 O 3 PIN photodiode exhibits good responsivity to incident light wavelengths in the UV-A, UV-B, and UV-C regions. While the NiO x layer is considered to be responsible for providing good photoresponsivity in the UV-A and UV-B regions, a highly resistive (near-intrinsic) β -Ga 2 O 3 layer is required for the absorption of incident UV-C light. A record detectivity of >10 11 cm Hz 0.5 W −1 for the UV-B and UV-C regions and >10 10 cm Hz 0.5 W −1 for the UV-A region is observed in the NiO x / β -Ga 2 O 3 heterostructure PIN photodiode during the self-powered operation. The results presented in this study are promising and instigate device design strategies for (ultra)wide bandgap semiconductor-based broadband UV PIN photodetectors.