Impact of metal nano-grating phase-shift on plasmonic MSM photodetectors

In this paper, finite difference time-domain (FDTD) method is used to simulate the light absorption enhancement in a plasmonic metal-semiconductor-metal photodetector (MSM-PD) structure employing a metal nano-grating with phase-shifts. The metal fingers of the MSM-PDs are etched with appropriate depths to maximize light absorption through plasmonic effects into a subwavelength aperture. Simulation results show that the nano-grating phase-shift red-shifts the wavelength at which the light absorption enhancement maximum, and that the combined effects of the nano-grating groove shape and the nano-grating phase-shift, degrade the light absorption enhancement by up to 50%.