Self-aligned silicon fins in metallic slits as a platform for planar wavelength-selective nanoscale resonant photodetectors.

We propose and demonstrate a novel nanoscale resonant metal-semiconductor-metal (MSM) photodetector structure based on silicon fins self-aligned to metallic slits. This geometry allows the center wavelength of the photodetector's spectral response to be controlled by the silicon fin width, allowing multiple detectors, each sensitive to a different wavelength, to be fabricated in a single-step process. In addition, the detectors are highly efficient with simulations showing ~67% of the light (λ = 800 nm) incident on the silicon fin being absorbed in a region of thickness ~170 nm whereas the absorption length at the same wavelength is ~10 µm. This approach is promising for the development of multispectral imaging sensors and low-capacitance photodetectors for short-range optical interconnects.