Low-Power Ionically Tunable Bilayer MoS₂ Synaptic Transistors

Electrochemical random-access memory (ECRAM) devices offer the possibility of highly linear, energy-efficient conductance modulation via electrochemical doping. This makes them attractive as synaptic weights for neuromorphic applications. Herein, we demonstrate inorganic ECRAM transistors with two-dimensional (2D) bilayer MoS₂ channels exhibiting both ionic and electrostatic gating. Our devices show electrochemical modulation of the channel conductance and electrostatic gating to achieve idle-state leakage currents of I_D < 100 fA (measurement limit). These unique capabilities are enabled by the 2D semiconductor channel, which supports both electrostatic (conventional field effect) and electrochemical, non-volatile gating. Unlike oxide-based ECRAMs, which typically operate in a degenerately doped regime, the crystalline 2D channel has a low baseline carrier density, which can be modulated electrostatically. Our devices demonstrate highly linear and symmetric training characteristics, evaluated using synaptic metrics commonly applied to memristive devices. These findings highlight the potential of 2D-based ECRAM devices for power-efficient synaptic electronics.