Hydrogen‐Induced Electronic Modulation at MoS ₂ /SiO ₂ Interfaces

ABSTRACT Two‐dimensional (2D) transition metal dichalcogenides (TMDs) are being explored in electronic and optoelectronic applications, including electrochemical random‐access memories (ECRAMs). ECRAMs are three‐terminal electrochemical neuromorphic devices in which a gate bias inserts or extracts ions (e.g., H + ) into or from a channel through a solid electrolyte, thereby modulating its conductivity. In thin‐film oxide channels, post‐pulse ion diffusion into the channel depth gives rise to a slow transient in obtaining the stable conductance state. Monolayer 2D TMD channels eliminate channel depth and could remove this contribution to transient, accelerating device programming. However, whether H insertion can modulate conductivity in 2D TMD channels remains to be determined. Here, we assess hydrogen incorporation at monolayer MoS 2 /SiO 2 interfaces using atomistic simulations with varying SiO 2 surface terminations. In the absence of sulfur vacancies, H favors incorporation on the SiO 2 surface when dangling bonds are present, leaving MoS 2 electronically decoupled from H. Once the oxide surface is saturated, H adsorbs onto or incorporates into MoS 2 , acting as an n‐type dopant. With sulfur vacancies, H stably incorporates into the vacancy and produces a similar n‐type effect. We experimentally verified these predictions in protonic ECRAM devices with monolayer MoS 2 channels: hydrogen insertion increased conductance, while hydrogen extraction decreased it, consistent with electron doping. Our findings confirm that H can modulate the conductivity of 2D monolayer MoS 2 channel at the interface with oxide electrolytes in ECRAMs and provide the underlying mechanisms.