First-principles study on the design and performance optimization of MoS _₂ - and SnS ₂ -based RRAM with high switching ratio and low energy consumption

Abstract Resistive random-access memory (RRAM) has garnered significant attention owing to its advantages of ultra-simple structure, high storage density, fast read/write speeds, low power consumption, and facile miniaturization and integration. In this work, first-principles calculations were employed to investigate the resistive switching performance and underlying mechanisms of MoS _₂ - and SnS _₂ -based RRAM devices. Additionally, the device performance was optimized by inserting graphene layers into the resistive switching layer. The results demonstrate that Ag/SnS _₂ /Pt RRAM outperforms Ag/MoS _₂ /Pt RRAM, exhibiting lower power consumption and a higher switching ratio. This superiority stems from the fact that the interlayer gap radius of SnS _₂ is larger than the ionic radius of silver ions (Ag ⁺ ), enabling Ag ⁺ to penetrate the atomic interior under an electric field. Furthermore, the van der Waals interlayer gap radius in SnS _₂ -based RRAM is larger than that in MoS _₂ -based RRAM, which facilitates the formation of a shorter conductive filament path. Consequently, this results in lower operating voltages and more distinct high-low resistance transitions. Moreover, the insertion of graphene layers induces Fermi level alignment at the interfaces, promoting the formation of space charge regions and the generation of internal electric fields. This enables the RRAM to achieve a higher switching ratio at lower voltages, thereby enhancing its overall performance.