Electrode-Assisted Switching in Memristors Based on Single-Crystal Transition Metal Dichalcogenides

The recently demonstrated nonvolatile resistive switching in transition metal dichalcogenides (TMDs) exhibits very different responses depending on the crystal quality, and the underlying mechanisms are yet to be elucidated. In this study, we utilize first-principles approaches to link the resistance-switching behavior in monolayer single-crystal TMDs to a semiconductor-to-metal transition. We analyze the electronic structure and charge transport properties in these systems by utilizing density functional theory and quantum transport calculations to compare the impact of different electrodes on the modulation of the junction resistivity. We specifically show that metal electrodes play a prominent role in assisting the transition between the semiconducting 1H and metallic 1T' phases in the TMD layer. Our results yield variations in conductivity in agreement with those found in experimental work. Analysis of defective layers indicates that the primary role of vacancies and substitutions is to lower the energy difference between the 1H and the 1T' phases rather than varying the conductance in these systems through defect levels. Overall, these results provide an explanation of the memristive behavior in single-crystal TMDs, proving helpful toward the development of flexible electronics and neuromorphic computing applications.