POST-ANODIZATION FILTERED ILLUMINATION OF POROUS SILICON IN HF SOLUTIONS - AN EFFECTIVE METHOD TO IMPROVE LUMINESCENCE PROPERTIES

A useful method is presented to improve the luminescence efficiency of porous silicon (PS) based on the post-anodization illumination of samples in HF solutions. In the present method the illumination is performed by a white lamp through sharp-cut long-wavelength-pass filters to remove the short wavelength component from the illumination light. The PS samples prepared by this method exhibited the visible photoluminescence (PL) with an efficiency of one order of magnitude higher than those illuminated without filters. The efficiency improvement is attributed to the reduction of the deteriorative surface oxidation of Si crystallites in PS. The filtered illumination technique is also useful to produce a larger PL blue shift and precise control of PL spectra.