Anodization Time Dependent Photoluminescence Intensity of Porous Silicon

摘要

The photoluminescence (PL) intensity first increases with anodization time (t_a) and then decreases at very large t_a. The increase in PL intensity with t_a may be understood if the PL intensity is taken to be proportional to the effective volume of porous silicon (PS) layer under the probe laser beam. The effective volume of PS layer will be proportional to its thickness and reciprocal to the porosity. For a fixed anodization condition, the thickness and porosity both increase with t_a. The increase in thickness increases the effective PS volume, while the increase in porosity causes the effective volume to decrease. Therefore, the intensity variation is governed by these two parameters: thickness and porosity. The observed results suggest that the thickness dominates the PL intensity initially and then the porosity becomes more important for very long t_a. The PS layers prepared under ambient light illumination also exhibited the similar behaviour. The intensity variation with t_a was explained as the interplay of thickness and porosity variations with t_a.