Hot Electron Dynamics in MoS2/Pt Van Der Waals Electrode Interface for Self‐Powered Hot Electron Photodetection

Abstract

Abstract Hot electron photodetection provides a powerful platform for photosensing beyond the bandgap of a semiconductor. High‐performing hot electron photodetection has been reported in 2D transition metal dichalcogenide material‐based devices without the support of plasmonic metal nanostructures but with planar metal electrodes. However, the mechanism driving hot electron dynamics in 2D transition metal dichalcogenide devices has not been explored. Here, we uncover the hot electron transfer in MoS2 and Pt van der Waals (vdW) metal electrodes by transient reflection spectroscopy, revealing a sub‐picosecond transfer time of hot electron and a decelerated recombination process in MoS2 at the below bandgap photoexcitation compared to the pristine MoS2. With an independent photocurrent mapping, the ultralong diffusion is revealed in MoS2/vdW metal electrode and a self‐powered near‐infrared (NIR) photodetector is demonstrated with a high responsivity of 6 mA W−1 and detectivity of 9 × 109 Jones at a wavelength of 1062 nm by integrating Pt and Ag asymmetric vdW electrodes into MoS2. The results will pave the way for the next generation of hot‐electron‐based self‐powered optoelectronic devices.

Keywords

• hot electron dynamics
• self‐powered
• transient reflection spectroscopy
• van der Waals electrode