Role of an electrolyte and substrate on the stability of porous silicon

Abstract

Porous silicon (PS) layers were prepared by anodization on polished and textured substrates of (1 0 0) Si for a fixed anodization time at different current densities in different HF-based electrolytes. Highly stable, mechanically strong, hydrogen-passivated surface and thick porous silicon films have been obtained using HF:ethanol-based electrolyte on textured silicon substrates. Porous silicon formed using HF:ethanol as an electrolyte exhibits superior properties compared to porous silicon formed using HF:H 2O 2-based electrolyte at the same current density, time of anodization and type of substrate. Porous silicon films formed on textured substrates exhibits higher porosity and photoluminescence efficiency, negligible PL decay, better mechanical strength, adherence to the substrate, non-fractured surface morphology and lower stress compared to porous silicon formed on polished silicon substrates at the same current density for both ethanol and H 2O 2-based electrolytes, respectively. Use of textured silicon substrate and ethanol-based electrolyte is a key parameter for the formation of tailored-made porous silicon films for device applications.