Performance improvement of plasmonic-based thin film assisted MSM-PDs

This paper presents numerical study on a novel type of plasmonic-based metal-semiconductor-metal photodetector (MSM-PD) for extraordinary light absorption, which can drastically modify transmission spectra when a thin film is designed inside the central subwavelength slit. This strategy assists to recover non-propagating evanescent waves at nano-scale. Furthermore, by focusing on metallic nanostructures and surface plasmon polaritons (SPPs), and their contribution to the confinement of light in subwavelength scale, we introduce the concept of plasmonic lens that significantly reduces metal induced energy losses. The proposed novel photodetector with a thin film on the central slit assists the device to absorb ∼280-times more light than the bare slit plasmonic-based MSM-PDs.