Multi‐Level Saturation Current Encoding in Two‐Dimensional Ferroelectric Source‐Gated Transistors

ABSTRACT Synaptic devices for low‐power neuromorphic systems require state variables that are robust against read‐bias variations while supporting multi‐level, non‐volatile operation. Encoding synaptic states directly in voltage‐invariant saturation current represents an attractive, yet underexplored approach, as it requires strong and well‐defined current saturation that is difficult to achieve in conventional memristor or memtransistor architectures. Here, a reconfigurable 2D material–based Source‐Gated Transistor (SGT) is demonstrated as a proof‐of‐concept ferroelectric memtransistor by integrating ferroelectric α‐In 2 Se 3 source contact with a high‐mobility MoS 2 channel. The device exhibits strong current saturation at ∼0.5 V d with an output impedance of ≈8 GΩ. The saturation current is non‐volatilely programmed into multiple levels spanning more than an order of magnitude via ferroelectric switching. Operando Kelvin‐Probe Force Microscopy (KPFM) suggests that the strong saturation of the SGT is due to lateral depletion at the MoS 2 ‐In 2 Se 3 interface. Scanning Photocurrent Microscopy (SPCM) reveals a ferroelectric switching‐dependent photoresponse at the MoS 2 ‐In 2 Se 3 interface, pointing to the built‐in field at the heterointerface as the source of the lateral depletion. These results identify saturation current, rather than linear resistance, as a candidate programmable, non‐volatile device parameter enabled by ferroelectric source‐gated architectures, and suggest its potential application for read‐bias‐tolerant operation in future low‐power neuromorphic devices.