Employing defected monolayer MoS₂ as charge storage materials

Recently, various two-dimensional (2D) materials have been employed in charge trapping memories as the charge trapping layer instead of conventional metal/semiconductor thin films or discrete particles. Such ultra-thin charge trapping layers are beneficial to the development of miniaturized devices, which is a trend in modern semiconductor technology. 2D MoS₂ is an alternative charge trapping material, but previous investigations have been limited to their multilayers. Here, we present the study on employing monolayer MoS₂ as charge trapping layer in charge trapping devices. We found that intrinsic monolayer MoS₂ is less effective for charge trapping; while defective monolayer MoS₂ shows enhanced charge storage capacity. By employing argon plasma treatments, we are able to control the defect density in monolayer MoS₂ and the memory window of monolayer MoS₂ based charge trapping devices can vary from 1.01 to 5.14 V at a sweeping voltage of ±20 V and program/erase slope from 0.06 to 0.32. Optimized devices show ∼1 ms program/erase speed, >70% charge retention after ∼7000 s and good endurance properties with >1000 cycles. The enhancement of the memory window is attributed to the localized charge tapping sites in defected monolayer MoS₂. This work would provide insights for the improvement of storage capacity through defects engineering in the atomically thin 2D materials.