Optical and morphological properties of porous silicon grown at low hydrofluoric acid concentration by electrochemical anodization

In this work the correlation of the photoluminescence (PL) and optical absorption spectra with low concentrations of hydrofluoridic acid (HF) within the range of 0.5 up to 5.5wt% is investigated. Therefore, P-type <;100> silicon wafers with resistivity of 7.0Ωcm were electrochemically etched in HF:water:ethanol mixture at different concentrations. The absorption spectra were measured from 1.25 to 3.75eV and compared with transitions of the morphological structure of porous silicon (PS). In addition, we used a Gaussian fitting procedure on the band energy structures for modeling the PS optical absorption spectrum.