Surface Dual Composite Nanostructure for Improving Visible Light Absorption in Thin Silicon Films

Visible light communication has attracted significant attention due to advantages such as high transmission speed, good security, high confidentiality, environmental protection, and lack of need for spectrum authorization. Herein, the problem of absorption of light in the visible band in thin silicon films is examined, and a dual composite nanostructure array based on nanoholes of two sizes is proposed to increase visible light absorption. Light absorptivity was determined to be greater than 80% at wavelengths between 400 and 678 nm. Moreover, using finite-difference time-domain numerical simulations, the distributions of the electric field at specific wavelengths were obtained, the propagation modes at these wavelengths were examined, and the effect of these modes was analyzed according to the electric field distributions. The proposed dual composite nanostructured silicon film can be used in photovoltaic devices to improve visible light absorption.