Light trapping and optical absorption enhancement in vertical semiconductor Si/SiO2 nanowire arrays**Project supported by the Science and Technology Project of Zhejiang Province, China (Grant No. 2017C31120).

Abstract

The full potential of optical absorption property must be further cultivated before silicon (Si) semiconductor nanowire (NW) arrays become available for mainstream applications in optoelectronic devices. In this paper, we demonstrate both experimentally and theoretically that an SiO2 coating can substantially improve the absorption of light in Si NW arrays. When the transparent SiO2 shell is coated on the outer layer of Si NW, the incident light penetrates better into the absorbing NW core. We provide the detailed theoretical analysis by a combination of finite-difference time-domain (FDTD) analysis. It is demonstrated that increasing the thickness of the dielectric shell, we achieve 1.72 times stronger absorption in the NWs than in uncoated NWs.