Performance Enhanced of Metal-Semiconductor-Metal Ultraviolet Photodetector Enabled by ZnO/MXene/ZnO Sandwich Structure Achieved Through the Hot-Electrons Injection in MXene Nanoflakes

The optimized metal-semiconductor-metal (MSM) ultraviolet photodetector (UVPD) based on ZnO/MXene/ZnO (ZMZ) sandwich structure is reported here. Since introducing ZMZ, the photoelectric performance of the UVPD has increased, which benefited from the cooperation between the interface electron depletion layer and injection of hot electrons (HEs), triggering the "storage and ejection" behavior of electrons. In general, under 365-nm laser illumination (6.25 mW/cm2), the Responsivity ( ${R}_{p}$ ) and Detectivity ( ${D}^{\ast }$ ) are almost unexpectedly increased by approximately an order of magnitude compared with pristine ZnO-based UVPD. More specifically, the ON/OFF ratio, ${R}_{p}$ , and ${D}^{\ast }$ are about > $10^{{3}}$ , 25.48 mA/W, and > $10^{{11}}$ Jones, respectively. Further, the long-term stable performance of the flexible ZMZ-based UVPD can also be observed after the 1000th bending cycle. And especially, the maximum attenuation coefficient (AC) of photocurrent is only ~5.75%. This work may offer a meaningful strategy for designing and improving the performance of ZnO-based UVPD in the future.