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

초록

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-In2Se3 source contact with a high-mobility MoS2 channel. The device exhibits strong current saturation at ∼0.5 Vd 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 MoS2-In2Se3 interface. Scanning Photocurrent Microscopy (SPCM) reveals a ferroelectric switching-dependent photoresponse at the MoS2-In2Se3 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. © 2026 The Author(s). Advanced Functional Materials published by Wiley-VCH GmbH.

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