Nanocrystal size modifications in porous silicon by preanodization ion implantation

A tuning of the nanocrystal sizes in porous silicon has been obtained by self-ion implantation in p-type silicon wafers before the anodization treatment. Sample porosity, luminescence spectra, Raman scattering, and transmission electron microscopy have been used to determine the structure of porous silicon samples. A porosity increase, a blue shift of the luminescence peak, a widening of the phonon resonance, and a decrease in the size features revealed by transmission electron microscopy (TEM) images are observed by increasing the ion implantation dose. It is suggested that this effect results from the increased resistivity of the Si wafer caused by the ion implantation damage.