High-performing BP/MoTe₂ mid-infrared photodetectors integrated with silicon waveguides

Developing high-performing and silicon compatible mid-infrared photodetectors will greatly benefit mid-infrared silicon photonics, useful to chemical sensing and medical diagnostics applications. But currently, it remains challenging to integrate mid-IR optoelectronics, such as II−VI or III−V semiconductors, with silicon photonics due to the mismatched lattice constant. To this regard, using the emerging two-dimensional (2D) materials has been considered as an alternative approach, as they could offer a wide variety of band gaps and can be assembled with each other to form van der Waals heterostructures. Among diverse 2D materials, black phosphorus (BP) is promising candidate for mid-IR applications, because it owns a direct and narrow band gap. In this talk, we will introduce a new type of hybrid photodetector, which is composed of black phosphorus/molybdenum ditelluride van der Waals heterostructures integrated with a silicon-on insulator waveguide. Our mid-infrared optoelectronic characterizations indicate our device could exhibit high responsivity (up to ~0.85 A/W) and ultrafast rise/decay time (~30ns and ~58ns, respectively) at room temperature condition. In addition, we show its noise equivalent power could be comparable to commercially available photodetectors. Such features suggest its usefulness to practical applications.