Porous Silicon's fractal nature revisited

Abstract

Fractal nature of porous silicon (Si), where porous nanowires (NWs) of Si has been observed inside the porous membrane matrix, has been revisited this time by metal assisted chemical etching (MACE) also known as metal induced etching or MIE. While carrying out MACE of Si wafer with silver nanoparticles (AgNPs) as the etching metal, it is observed that non vertical chemical etching take place. An SEM study reveals that the usual well aligned SiNWs, approximately 50 nm thick, consists of nanometer wide pores in themselves. The nanometer sized pores in turn results in Si NSs of a few nanometers in these thick looking SiNWs and are capable of showing quantum confinement effects. The SEM and TEM studies have been consolidated to model the growth mechanism for the observed fractal porous Si. © 2018 Elsevier Ltd