Robust trap effect in transition metal dichalcogenides for advanced multifunctional devices

Defects play a crucial role in determining electric transport properties of two-dimensional transition metal dichalcogenides. In particular, defect-induced deep traps have been demonstrated to possess the ability to capture carriers. However, due to their poor stability and controllability, most studies focus on eliminating this trap effect, and little consideration was devoted to the applications of their inherent capabilities on electronics. Here, we report the realization of robust trap effect, which can capture carriers and store them steadily, in two-dimensional MoS_2xSe_2(1-x) via synergistic effect of sulphur vacancies and isoelectronic selenium atoms. As a result, infrared detection with very high photoresponsivity (2.4 × 10⁵ A W^-1) and photoswitching ratio ( 10⁸), as well as nonvolatile infrared memory with high program/erase ratio ( 10⁸) and fast switching time, are achieved just based on an individual flake. This demonstration of defect engineering opens up an avenue for achieving high-performance infrared detector and memory.