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 (MoTe2) Schottky photodiode integrated on a silicon nitride (Si3N4) 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 × 1011 Jones, and a response rise time (τr) 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 × 1011 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.