Modeling of High and Low Resistant States in Single Defect Atomristors

Abstract: Resistance-change random access memory (RRAM) devices are nanoscale metal-insulator-metal structures that can store information in their resistance states, namely the high resistance (HRS) and low resistance (LRS) states. They are a potential candidate for a universal memory as these non-volatile memory elements can offer fast-switching, long retention and switching cycles, and additionally, are also suitable for direct applications in neuromorphic computing. In this study, we first present a model to analyze different resistance states of RRAM devices or so-called "atomristors" that utilize novel 2D materials as the switching materials instead of insulators. The developed model is then used to study the electrical characteristics of a single defect monolayer MoS$_{2}$ memristor. The change in the device resistance between the HRS and LRS is associated to the change in the tunneling probability when the vacancy defects in the 2D material are substituted by the metal atoms from the electrodes. The distortion due to defects and substituted metal atom is captured in the 1D potential energy profile by averaging the effect along the transverse direction. This simplification enables us to model single defect memristors with a less extensive quantum transport model while taking into account the presence of defects.