Polarization-Insensitive Metal–Semiconductor–Metal Nanoplasmonic Structures for Ultrafast Ultraviolet Detectors

Abstract

We propose a theoretical design principle of polarization-insensitive metal–semiconductor–metal (MSM) structure for ultraviolet photodetectors based on one-dimensional nanogratings. Because the Fabry–Perot cavity modes supported by a 100-nm-thick ZnO layer with nanostructures for transverse electric and transverse magnetic polarized incidence overlap with each other, a polarization-insensitive absorption enhancement for the ZnO layer at UV wavelengths is achieved, which can be implemented as a nano-interdigitated electrode to address a long-existing limitation between the speed and the responsivity for conventional MSM photodetectors.