40 GHz waveguide-integrated two-dimensional palladium diselenide photodetectors

Hybrid integration of two-dimensional (2D) materials with photonic integrated circuits can enable additional functionality in planar waveguides based on excellent optical and electrical properties of 2D materials. 2D layered palladium diselenide (PdSe₂) has a narrow energy bandgap and high carrier mobility, and its stability under normal laboratory environment conditions makes it of interest for use as high-performance infrared photodetectors. In this work, we propose and experimentally demonstrate a high-speed waveguide-integrated photodetector which uses chemical vapor deposition grown PdSe₂ transferred onto a silicon waveguide. At 1550 nm wavelength, the photodetector can be operated without external bias with a responsivity of 0.57 mA/W and a responsivity of 20 mA/W at 6 V bias voltage. The detector had an impulse response full-width-half-maximum pulse width of about 11 ps, corresponding to a 3-dB bandwidth of 40 GHz.