Synthesis and characterization of porous platinum layers deposited on highly doped N-type porous silicon by immersion plating

In this article, we report on the synthesis and characterization of porous platinum layers on top of highly doped (0.007-0.02 and 0.001-0.003 Omega cm) n-type porous silicon by immersion plating. Porous silicon samples of different morphologies were prepared by electrochemical etching. Plating was performed by simple immersion of the porous samples in HF-containing hexachloroplatinate solutions for some minutes. Scanning electron microscopy showed that the deposits attained up to 8 mu m depth. Moreover, the achieved platinum deposits have a random pore structure, whereas the original porous silicon substrates show an organized honeycomb-like parallel pore array. Electron probe microanalysis measurements showed that the deposits have very good in-depth homogeneity, indicating also that almost all silicon originally present was etched away by platinum. The electrochemically active surface area of the platinum deposits was determined to be on the order of 80 m(2)/cm(3) by cyclic voltammetry. (c) 2006 The Electrochemical Society.