High-Speed, High-Responsivity on-Chip Monolayer MoS₂Photodetector at Telecom Wavelengths

Significant research efforts have focused on developing novel optoelectronic devices utilizing two-dimensional (2D) transition-metal dichalcogenides (TMDs), motivated by their strong light–matter interactions and unique material properties. Photodetectors simultaneously achieving high-speed and high-responsivity performance are particularly crucial for applications such as high-data-rate interconnects operating at telecom wavelengths. However, the intrinsically limited carrier mobilities in TMDs present a fundamental bottleneck for a high-speed operation. Here, we demonstrate high-performance monolayer MoS₂ photodetectors fabricated via chemical vapor deposition (CVD) and monolithically integrated with a dielectric waveguide. The Au–MoS₂–Au device architecture minimizes carrier transit path lengths while exploiting the short lifetime of hot electrons, yielding a measured bandwidth of ∼3.28 GHz. Concurrently, the device achieves a high responsivity of 144 mA W^–1 at 1529.3 nm, attributed to an integrated tapered-waveguide design that significantly enhances the light–matter interaction region. This in situ synergistic integration of wafer-scale CVD-grown TMDs with planar, etch-free photonic circuits establishes a versatile platform for realizing high-performance on-chip optoelectronic devices.