Enhancement of polarization response in UVA and UVC wavelength with integrated sub-wavelength metal-grids

Abstract

The sensitive detection of polarization-states of ultraviolet (UV) light is enssential for many optoelectronic applications, such as UV communication and polarization imaging. However, the anisotropic response of the polarization detectors based on pristine wide-bandgap materials are quite weak, hindering UV polarization detectors from further application. In this paper, we present highly polarization-sensitive photodetectors based on Ga2O3 (UVC) and ZnO (UVA) materials by integrating with sub-wavelength metal nanowires. The photoresponse of pristine ZnO photodetectors to polarized UVA light turns from isotropic to centrosymmetric after introducing 70 nm width/space metal grids. For Ga2O3 UVC photodetectors, the polarization rejection ratio was increased from 7.5 to 49 after integrated with 50 nm width/space metal grids. The enhancement of photoresponse to polarized UV light by using sub-wavelength metal grids is studied via FDTD simulation. This work provides an effective way for wide-bandgap semiconductors to improve their sensitivity to UV polarized light, and could be used in UV polarization detection, imaging and communication.