Plasmon-induced Hot-electron Injection Effect: Mechanism of Performance Enhancement for ZnO MSM Hybrid Photodetector by Introducing Ag NWs and MXene

Abstract In this paper, a performance-enhanced hybrid ultraviolet metal-semiconductor-metal (MSM) photodetector (UVPD) has been produced. This device incorporates a mixed photosensitive layer consisting of MXene nanoflakes that are covered on a thin film formed by Ag nanowires (NWs) wrapped in ZnO nanoparticles (NPs). This configuration, referred to as ZnO@Ag NWs/Mxene, capitalizes on the hot electrons generated by the Localized Surface Plasmon Resonance (LSPR) phenomenon occurring in the Ag NWs and MXene. These hot electrons possess sufficient energy to traverse the interface depletion layer and reach the ZnO layer. Therefore, the injected hot electrons serve as additional photo carriers in the ZnO layer, thereby increasing the number of photo-generated carriers and improving the carrier concentration in ZnO. The improved UVPD device exhibits an amplified photocurrent of ~ 2499.35 nA at 5 V, under a light intensity of 6.52 mW/cm2 and a wavelength of 365 nm. Simultaneously, it achieves enhanced performance indices, including an On/Off Ratio of ~ 984.19, a responsivity (Rp) of ~ 66.87 mA/W, and a detectivity (D*) of ~ 1.82 × 1011 jones. These values represent a significant improvement compared to devices based solely on the ZnO configuration, with enhancements of ~ 24.90, 3.93, 23.38, and 9.33 times, respectively. Based on the obtained results, it can be inferred that employing the hot electron injection effect to design and enhance the performance of optoelectronic devices based on wide band gap semiconductors is a reasonable and effective strategy.