Absorption enhancement of In0.53Ga0.47As photodetector with rear plasmonic nanostructure

In this paper, metallic back structure with one dimensional periodic nano-ridge is attached to the capping layer of the In0.53Ga0.47As photodetector with 100 nm absorption layer. We present finite difference time domain (FDTD) simulation to analyze the optical absorption enhancement of the photodetector. By comparing with the photodetector with planar metallic film, simulation results show that by introducing the nanostructure a 2.8 times and a 3 times absorption enhancements can be achieved under transverse magnetic (TM) and transverse electric (TE) polarized plane wave illuminations, respectively. Increasing the period of the nanostructure, the absorption enhancement peak positions exhibit a red shift. In addition, the optimization of the metal grating height and width is also crucial for maximizing the absorption enhancement. The absorption enhancements are well explained by surface plasmon polaritons and Rayleigh Anomalies phenomena. Solid simulation and theoretical results are both presented with good agreement with each other.