A Comprehensive Study on the Impact of Various Nano-gratings on MSM-PDs for Enhancement in the Light Absorption

Abstract

In this paper, we have analyzed metal
semiconductor-metal photodetectors (MSM-PDs) with different
nano-grating structures or shapes to improve the light absorption
capacity into the device in details for high-speed communication
systems and networks. The plasmonic-based MSM-PD structure
demonstrates a significant improvement in light absorption
capacity for the developed device compared to conventional MSM
PDs i.e., devices that have not employed the nano-gratings. The
light absorption capacity of the device is varied with the variation
of geometrical shapes and parameters of the nano-gratings, such
as the nano-grating height, slit width and so on. These nano
grating structures are assisting in light transmission through the
central slit (i.e., subwavelength apertures) efficiently, resulting in
the excitation of surface plasmon polaritons (SPPs) as the incident
photons interact with the nano-gratings/ nano-corrugations. This
improved light transmission in the central slit along with excited
SPPs results in resonant light absorption in the device. This means
the light trapped inside the central slit is triggered by the SPPs to
a higher order magnitude. This causes the light absorption
enhancement for the device, i.e., more light is transmitted through
the device instead of reflecting back to the surface. The simulation
results demonstrated that the light absorption enhancement factor
(LAEF) for these devices have improved dramatically due to the
nano-gratings. For modeling and simulation of these devices, Opti
FDTD tool is used which is based on finite difference time domain
(FDTD) method. The application of these simulated devices is in
the range of 800-850-nm. The simulation results are suitable for
the design of nano-structured MSM-PDs that can be used in high
speed communication systems and sensor network systems.