Near-infrared optical characteristics of composite Ag-porous Si dielectric film for solar devices

Ag-porous Si (Ag-pSi) composite as metallo-dielectric based periodical lattice nanostructure is proposed and studied to improve the light efficiency in such structure in near-infrared range of 750-3000 nm. To achieve this, Finite-Differential Time-Domain (FDTD) implements were applied in analyzing the effects of number of layers (nLs) as well as porosity on optical characteristics of reflection, transmission and absorption using “FDTD solutions”. Perfectly matched layers (PML) and periodic boundary conditions (PBC) were selected as suitable boundaries for this simulation. The results revealed that these highlighted optical properties through the composite are influenced by variation in the nLs and porosity in near-infrared wavelengths. The reflection and transmission spectra presented contrasting patterns. Optimum transmission was attained at 80% porosity with the thickness higher than 500 nm. For the composite Ag-pSi, all the peaks found in these optical properties tended towards higher wavelengths as compared to the case of the composite Ag-Air which had an empty structure. The optimum absorption was improved by 10% with the incorporation of pSi into the Ag material. Therefore, the enhancement of optical properties in this proposed design can be achieved by controlling both the nLs and porosity.