Design of a silicon resonant cavity enhanced photodetector based on the internal photoemission effect at 1.55 μm

In this paper, the design of a resonant cavity enhanced photodetector, working at 1.55 mu m and based on silicon technology, is reported. The photon absorption is due to the internal photoemission effect over the Schottky barrier at the metal-silicon interface. The photodetector is composed of a silicon layer in between multiple layers of Si-SiO2, as a bottom mirror, and a thin Au film and dielectric coating, as a top mirror. In order to estimate the quantum efficiency, we take advantage of the analytical formulation of the internal photoemission effect (Fowler theory) and its extension for thin films, while for the optical analysis of the device, used to calculate mirror reflectivities and active layer absorptance, a numerical method based on the transfer matrix method has been implemented. Our numerical results prove a significant enhancement of the efficiency obtained at resonant wavelengths by a very thin absorbing layer.