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 similar to 1 ms program/erase speed, >70% charge retention after similar to 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.