Waveguide-Integrated MoS₂ Field-Effect Transistors on Thin-Film Lithium Niobate with High Responsivity and Ultra-Low Dark Current

This study investigates the photoelectric performance of MoS2-based field-effect transistors (FETs) integrated with a thin-film lithium niobate (TFLN) waveguide platform. The MoS2 FET demonstrates high photodetection capabilities across a broad wavelength range from visible to near-infrared (up to 1550 nm). By adjusting the gate voltage from 0 V to −25 V, the dark current is reduced by over 6 orders of magnitude, reaching approximately 2 pA. Under 635 nm illumination, the device achieves a maximum responsivity of 940 A/W (at an input power of 35 pW), an on/off ratio (Ilight/Idark) of 105, and a detectivity of 6.27 × 1014 W–1. Significant photoresponse is also observed at telecommunication wavelengths with a responsivity of 68.7 mA/W and a detectivity of 4.58 × 1010 W–1 at 1310 nm. Additionally, the response times is measured to be under 300 μs across all tested wavelengths. The combination of two-dimensional material FET and TFLN offers an attractive platform for realizing high-performance optoelectronic devices and multifunctional integrated photonic circuits.