Design of InAs nanosheet arrays for high-performance polarization-sensitive infrared photodetection

Polarization-sensitive infrared photodetectors are widely needed to distinguish an object from its surrounding environment. Polarization-sensitive detection can be realized by using semiconductors with anisotropic geometry or anisotropic crystal arrangement, such as semiconductor nanowires and two-dimensional (2D) materials. However, these photodetectors show drawbacks in low light absorption, weak polarization sensitivity and stability issues. Here, we designed 2D InAs nanosheet based arrays that are highly suitable for polarization-sensitive infrared photodetection. By using the finite element method (FEM) based on COMSOL Multiphysics, we optimized the geometry of single free-standing InAs nanosheets, obtaining dichroic ratio up to 127 (average) in the wavelength range of 2-3 mu m by reducing the thickness and increasing the height. Extending this to a nanosheet array with an optimized geometry, an enhancement of the absorption intensity from 45% (for a single nanosheet) to over 67% with a dichroic ratio exceeding 50 in the wavelength range of 2-3 mu m can be achieved. Moreover, these unique light absorption properties are tolerant to incident angles up to 30 degrees. The design of such nanosheet array provides a new route for the development of high-performance infrared photodetectors for polarization photodetection.