Embedded graphene photodetectors for silicon photonics

Graphene has extraordinary electronic and optoelectronic properties such as high carrier mobility, large charge-carrier concentrations, tunability via electrostatic doping, wavelength-independent absorption, and relatively low dissipation rates. The combination of its electro-optical properties with its manufacturability and CMOS integrability makes graphene an extremely promising candidate for active photonic devices. Because of its two-dimensional appearance, graphene has a limited light absorption, which is not enough to fulfill the requirements of silicon photonics technology. Recently, the integration of graphene with silicon waveguides has been shown for on-chip applications. In these solutions graphene is placed on top and outside of the waveguide yielding only limited light-graphene interaction. We introduce novel photo-detector architecture by embedding CVD-graphene inside the slot layer of deposited high-k slot waveguides that are compatible with back-end-of-the-line manufacturing of photonic integrated circuits (PICs). This approach leads to a high light-graphene interaction due to the high mode concentration in the slot region. This results in enhanced absorption and enables a very compact photodetector design.