High-responsivity InSe/TaSe₂ photodetectors integrated on low-loss silicon nitride waveguides

Two-dimensional materials integrated with waveguides present a promising platform for the development of high-performance on-chip photodetectors due to their exceptional optoelectronic properties. In this study, we demonstrate both simulated and experimental results by fabricating and characterizing an InSe/TaSe₂ heterojunction photodetector on a low-loss silicon nitride waveguide. The fabricated device achieves a high responsivity of 2.54 AW^-1, an external quantum efficiency (EQE) of 592%, a noise equivalent power (NEP) of 12 nW, and a noise power detection ratio (NPDR) of 25.8 PAW^-3 at a source-drain voltage (V _sd) of 2 V. In particular, the responsivity of the InSe/TaSe₂ heterojunction exceeds that of the reference InSe-based photodetector by more than 50%. Additionally, when illuminated with laterally incident light through the waveguide, the photodetector exhibited significantly higher responsivity compared to the normal-incidence configuration, achieving approximately a 20-fold enhancement as a result of stronger light-matter interactions and the intrinsic properties of the heterostructure. These findings highlight the potential of on-chip heterojunction-based photodetectors for applications in sensing, imaging, and integrated communication systems.