Parallel or Interconnected Pores’ Formation through Etchant Selective Silicon Porosification

Abstract

Effect of oxidizer, present in the etching solution, on the surface morphology and microstructure obtained after porosification of p-type silicon wafer using metal assisted chemical etching has been studied here. The morphologies of Si wafers porosified using two different solutions namely HF/ H2O2 and HF/KMnO4 have been compared to establish how either of the oxidizers (H2O2 or KMnO4) should be chosen depending on the desired application. The comparative study reveals that either parallel pores with wire like structures or interconnected pores with cheese like structures can be obtained when H2O2 or KMnO4 respectively are chosen. Careful analysis of SEM images has been carried out using ImageJ to establish that samples prepared using KMnO4 are more porous due to aggressive etching. Additionally, experimental and theoretical Raman spectroscopic studies have been utilized to study the presence of low dimensional Si nanostructures of a few nanomaters size at the microscopic level in the porosified silicon.