Self-powered broadband ultraviolet photodetector based on MoSe2/ n-GaN heterojunction

The low power consumption and potential applications of self-powered ultraviolet (UV) photodetectors (PDs) in biomedical fields have attracted significant research interest, particularly for diagnostics, environmental monitoring, and wearable devices. We report the fabrication of MoSe2/n-GaN heterojunction by utilizing the r.f. magnetron sputtering system for self-powered broadband UV photodetection. The crystalline and structural quality of MoSe2 thin film was confirmed through X-ray diffraction and Raman spectroscopy. The field emission scanning electron microscopy characterization reveals the earthworm-like morphology of MoSe2 thin film. The fabricated MoSe2/n-GaN PD device exhibits self-powered photoresponse in the UV-C region with photoresponsivity of 35.7 mA/W and detectivity of 5.3 x 1010 Jones. For UV-A region, the MoSe2/n-GaN PD device shows a responsivity of 29.5 mA/W and detectivity of 3.15 x 108 Jones in self-powered operation and exhibited a high photoresponsivity of 31.7 A/W and detectivity of 2.1 x 109 Jones at 5 V. The fabricated PD device also showed a photoresponsivity of 1.6 A/W and detectivity of 1.26 x 108 Jones in the near infra-red region at 5 V. The facile root for integrating transition-metal dichalcogenides/GaN heterojunction-based PDs showed excellent light harvesting capability under self-powered and high photoresponse in a broad wavelength range.