Two-Dimensional Molybdenum Ditelluride Waveguide-Integrated Schottky Photodiode for Near-Infrared Detection

Two-dimensional (2D) materials hold great promise for high-performance photonic chip-integrated photodetectors, thanks to their outstanding electronic and optical properties as well as dangling-bond-free surfaces. In addition, the integration of 2D materials on silicon is seen as a promising structure to address the challenge of limited broadband light detection in silicon photonics. Due to the ultrathin nature of two-dimensional materials, their light absorption capacity is inherently limited. In this Letter, we present a high-performance molybdenum ditelluride (MoTe 2 ) Schottky photodiode integrated on a silicon nitride (Si 3 N 4 ) transverse waveguide. At 1550 nm, the waveguide-integrated photodetector exhibits excellent photoelectric characteristics at 0 V bias with a responsivity ( R ) of 0.32 A/W, a detectivity ( D *) of 4.39 × 10 11 Jones, and a response rise time (τ r ) of 190 μs. Furthermore, the photodetector also exhibits competitive detection performance across the wide band range of 850–1100 nm, with peak response observed at 900 nm corresponding to the R of 0.20 A/W and D * of 1.51 × 10 11 Jones under 0 V bias, respectively. The self-powered photodetector is characterized by its light weight, compact size, low energy consumption, and ability to autonomously perform photodetection without relying on an external power source. This innovative device offers a viable solution for the design and fabrication of integrated optoelectronic chips on passive substrates.