Effect of electrolyte pH value and current density on the electrodeposition of silver nanoparticles into porous silicon

Abstract

Nanostructured porous silicon (PS) can be used as a template for the growth of noble metal nanoparticles for the subsequent development of metal/semiconductor hybrid structures with application in several fields. The current work reports on the electrodeposition of silver nanoparticles (AgNPs) into columnar PS layers. In particular, the size, morphology, and surface density of the AgNPs grown into PS were studied as a function of the electrolyte pH value and the infiltration current density. Furthermore, the optical properties of the hybrid PS + AgNPs structures were analyzed. The experimental results show a remarkable reduction in the size of AgNPs and increased growth rate upon reducing the acidity of the electrolyte and upon increasing the current density. In addition, a remarkable reduction of the average reflectance is observed under specific fabrication conditions. In particular, as the pH values of the electrolyte increase, the optical reflectance decreases. This relation is attributed to the reduction in the AgNPs size. On the other hand, increasing the infiltration current density increases the average reflectance due to increasing surface density of the AgNPs. These results demonstrate that the size and shape of AgNPs can be controlled by adjusting the applied infiltration current density and the pH value of the electrolyte depending on the intended application.