Schottky-interface-controlled mode-reconfigurable photoresponse in all-2D MESFET

This is the authors' abstract. We don't add key points for this paper.

Mode-reconfigurable optoelectronic devices integrating fast photodetection and photosynaptic response are promising for adaptive visual sensing and neuromorphic preprocessing. However, most reported dual-mode devices still rely on global metal–oxide–semiconductor gating and uncontrolled dielectric-interface trapping, which limit local interfacial control and often require relatively high operating voltages. Here, we demonstrate a VSe2-gated WS2 van der Waals (vdW) metal–semiconductor field-effect transistor (MESFET) with Schottky-interface-controlled dual-mode photoresponse. The VSe2/WS2 Schottky contact induces strong depletion, enabling enhancement-mode-like operation at low gate voltage. By tuning the depletion region and interfacial photogating, the device switches from fast photodetection to persistent photosynaptic response. Under 520 nm illumination, the photodetection mode shows rise/fall times of 4.9/6.77 ms and a responsivity of 395 mA W−1. In the photosynaptic mode, the device exhibits excitatory postsynaptic current, paired-pulse facilitation, and a transition from short-term to long-term plasticity. The persistent response further enables temporal filtering for neuromorphic vision preprocessing. This work provides a strategy for low-voltage dual-mode optoelectronic devices based on vdW MESFETs.