Electron Irradiation Effect on 2-D WSe2 Phototransistors

Two-dimensional phototransistors are promising in use for target detection, communication, and remote control due to their high responsiveness, sensitivity, and wide detection band. When phototransistors are used in extreme environments, such as aerospace, they are inevitably impacted by external irradiation. Therefore, it has been an important issue to study the tolerance of phototransistors to the irradiation. In this article, we have conducted full-irradiation and local-channel-irradiation on the 2-D WSe2 phototransistors using electron beams. It has been found that irradiation increases the Schottky contact resistance and decreases the dark current ( I_{\mathbf {dark}} ) by 99.56% compared to the initial performance. With time annealing, the performance of phototransistors is stabilized after 168 h. Furthermore, the responsivity (R), external quantum efficiency (EQE), and specific detectivity ( D^{\ast } ) decrease by more than 99% due to the physical adsorption of carriers in the time annealing. Fortunately, the degradation caused by the physical adsorption can be recovered by the evacuation treatment. In general, WSe2 phototransistors are not tolerant to electron irradiation, and they should be avoided to exposure in electron irradiation to improve their lifetime.