This work describes the design and TCAD-based simulation of a high-speed self-powered ultraviolet (UV) photodetector based on a heavily p-type doped multi-layer graphene (p⁺-MLG) and lightly n-type doped ZnO nanowires (n⁻-ZnO NWs) heterojunction. The device structure is based on the utilization of the high built-in electric field across the heterointerface for effective carrier separation to support both self-biasing and photoconductive operations. Simulated outcomes show rectifying characteristics with a dark-mode and light-mode rectification ratios of 8.5 × 10³ and 5.2 × 10², respectively. Spectral response demonstrates a maximum photocurrent-to-dark current ratio at 350 nm. The device has an external quantum efficiency (QE) of 55.43%, maximum responsivity (R_i) of 0.16 A/W, detectivity (D^*) of 2.44 × 10⁹ Jones, and rapid photoswitching times with both rise time and fall time of 0.16 ns. Compared to previously reported graphene/ZnO photodetectors, the proposed heterostructure demonstrates enhanced photoswitching speed and efficient self-powered operation due to the optimized heterojunction design and strong internal electric field. p⁺-MLG/n⁻-ZnO NWs integration facilitates UV detection with mechanical flexibility and low power consumption, which makes the device of great interest for wearable and biomedical sensing devices.

Shonak Bansal ,Krishna Prakash ,Payal Patial ,Anupma Gupta