Morphological and optical characteristics of porous silicon structure formed by electrochemical etching

Porous silicon (PS) is defined as a composition of a silicon skeleton permeated by a network of pores or in other word, PS is a network of silicon nanowires and nanoholes which are formed when the crystalline silicon wafers are etched electrochemically in electrolyte solution such as hydrofluoric (HF) acid [1,2]. PS shows different features in comparison to the bulk silicon such as shifting of fundamental absorption edge into the short wavelength and photoluminescence visible region. The PS material possesses interesting characteristics such as larger surface to volume ratio, high-intensity of nano porous structure and low refractive index which lead to the potential application like filter, catalyst support, chemical sensor, anti reflection coating in solar cell and light emitting diode (LED) [3–6].