Role of Metal Nanoparticles in the Fabrication of Porous Silicon: A Material for Solar Cell Applications

Abstract

Metal-Assisted Chemical Etching method (MACE) has emerged as an effective tool to fabricate silicon nanostructures. This technique requires a catalytic mask that is commonly composed of a metal. In the present work, the role of Silver nanoparticles (AgNPs) in the etching mechanism of Porous Silicon (PS) is investigated by studying the effect of AgNP coverage on the surface porosity and the different properties of PS. XRD spectra consist of the two peaks corresponding to silicon and AgNPs respectively and the peak intensity of Ag decreased with an increase in etching time which indicates that as the etching time increases the dissolution of silver metal also increases. Thus, the pore depth depends on the dissolution of AgNP. The pore depth and porosity are calculated at different etching times by SEM analysis. It is observed that porosity is modifiable with the variation of AgNP coverage which in turn modifies the optical properties of PS. The porosity increased with the increase of etching time and the highest porosity obtained was 78% after 240 minutes. The refractive index of PS decreased with increasing porosity in the visible region. The variation of the refractive index results in the tuning of optical energy gap which is more essential in increasing the efficiency of solar cells.