Design and simulation of anti-reflecting nanostructure for visible shortwave infrared focal plane array detectors

InGaAs/InP Focal Plane Array (FPA) photodetector, which responses from 400nm-1700nm, is widely used in many applications, while its quantum efficiency in visible spectrum is commonly lower than Shortwave Infrared (SWIR) spectrum. In order to improve the quantum efficiency in visible spectrum, new methods need to be applied. Based on Mie scattering, sub-wavelength nanostructure arrays have been demonstrated that can be used as anti-reflecting mechanism in visible spectrum. Here we present the design and simulation of the parameters of nanostructure arrays, which aims at suppressing the reflection in visible spectrum, thus the transmittance of visible light from the back-illuminated side gets improved. Simulation results prove that designed nanostructure arrays can decrease the reflectance in visible spectrum, and integrating designed nanostructure arrays on ultra-thin back-illuminated layer can improve the transmittance, which improves the quantum efficiency of photodetector.