Unveiling the Carrier Dynamics and Trapping Behavior in High‐performance MoS ₂ Photodetector via Screening Interface Impurity

ABSTRACT Trap levels have a critical influence on the performance of 2D semiconductor devices. Particularly in the field of photodetectors, the time for trap‐captured carriers to be released is several orders of magnitude longer than that required for free carriers to recombine, which significantly constrains the decay/response time of photocurrent. In this work, we reduced the dark current of Gr/MoS ₂ /Gr field‐effect transistors by approximately ∼2 orders of magnitude by employing h‐BN for surface encapsulation of MoS ₂ . The h‐BN effectively isolated surface H ₂ O/O ₂ adsorption and passivated certain intrinsic surface defects, which reduced the effective trap density by ∼63%. At the same time, the recovery time of the photocurrent was reduced by up to ∼3 orders of magnitude. Moreover, we directly captured the decay process of photo‐generated carriers in real time and fitted the experimental data using a triple‐exponential decay kinetic equation. Which enabled us to analyze the decay kinetics of free carriers and trap‐induced carriers during the decay process. Through the construction of a trap dynamics model, we revealed the physical mechanism behind h‐BN encapsulation of MoS ₂ . This work provides a theoretical foundation for defect engineering in devices and the development of ultrafast photodetectors.