MoSe/WS heterojunction photodiode integrated with a silicon nitride waveguide for near infrared light detection with high responsivity.

We demonstrate experimentally the realization and the characterization of a chip-scale integrated photodetector for the near-infrared spectral regime based on the integration of a MoSe/WS heterojunction on top of a silicon nitride waveguide. This configuration achieves high responsivity of ~1 A W at the wavelength of 780 nm (indicating an internal gain mechanism) while suppressing the dark current to the level of ~50 pA, much lower as compared to a reference sample of just MoSe without WS. We have measured the power spectral density of the dark current to be as low as ~1 × 10 A Hz, from which we extract the noise equivalent power (NEP) to be ~1 × 10 W Hz.

Waveguide-integrated mid-IR photodetector and all-optical modulator based on interlayer excitons absorption in a WS/HfS heterostructure.

Novel 2D van der Waals semiconductors facilitate the formation of heterostructures and thus support bandgap engineering for atomically thin modern photonic applications. When these heterostructures form a type II band structure, interlayer excitons (ILEs) are formed as a result of the ultrafast charge transfer between the layers. Here, we present for the first time a waveguide-coupled, mid-IR photodetector and modulator based on the ILE absorption.