Schottky-Contacted WSe₂ Hot-Electron Photodetectors with Fast Response and High Sensitivity

Utilizing the short lifetime of hot electrons, ultrasensitive hot-electron photodetectors with fast response speed can be developed that have the potential to carve a niche among the photoconductive devices. Herein, high-performance WSe₂ photodetectors are fabricated based on hot-electron transportation, in which an ultrathin Al₂O₃ layer enables screening of high-energy hot electrons and promises ultrasensitive response to incident light, and the built-in electric field in Schottky junctions separates the photoinduced carriers for fast transient recovery. The hot-electron photodetectors demonstrated a high rectification ratio of 10⁷ and an extremely low dark current of 1 pA/μm with a high I_light/I_dark ratio of 1.8 × 10⁶. Moreover, a high responsivity of 3.69 A/W and detectivity of 2.39 × 10¹³ Jones at an incident light power of 5.0 μW/cm² are simultaneously achieved. The present strategy offers an alternative route for ultrasensitive photodetectors with fast response.