MoS 2 MESFET Phototransistor via Photogenerated Carrier‐Induced Schottky Depletion Width Narrowing

ABSTRACT The explosive growth of communication data traffic has driven the demand for efficient on‐chip photodetection platforms that combine high sensitivity, fast response, and compact integration. Two‐dimensional (2D) materials have emerged as promising candidates, attributed to their atomic‐scale thickness, tunable optoelectronic properties, and excellent compatibility with on‐chip integration. However, most 2D material photodetectors face a challenge in simultaneously achieving high responsivity and fast photoresponse speed. Here, we demonstrate a MoS 2 metal‐semiconductor field effect transistor (MESFET) phototransistor featuring a Pt‐MoS 2 Schottky gate. Distinct from photovoltaic photodetectors (low responsivity), photoconductive photodetectors (high dark current), and photogating photodetectors (slow response governed by trap states), the device exploits photogenerated carrier‐induced depletion width narrowing to convert a weak optical signal into a large source‐drain photocurrent via transconductance amplification, thereby achieving fast photoresponse (168 µs) and high responsivity (1.68 A/W) simultaneously while maintaining low dark current. These features enable the device to function as a low‐power light encoder for integrated optical communication applications, with time‐division multiple access (TDMA) achievable through multi‐device integration. Our study presents a Schottky‐gated MESFET phototransistor strategy for high‐performance 2D photodetection, offering a promising route toward practical on‐chip optoelectronic integration.