Formation of micrometer-sized electrical contacts on light-emitting porous silicon films

In the aqueous electrolyte of copper (II) chloride, metallic conducting thin films have been electrochemically deposited onto the top surfaces of porous silicon (PS) films. Employing the scanning electron microscopy (SEM), we have investigated the surface morphology for an original PS film, a lightly deposited PS film and a heavily deposited PS film, respectively. On the basis of the SEM micrographs, the surface roughness of each PS film is quantitatively analyzed. Our results have demonstrated that the originally rough surfaces of PS films can be smoothed by the electrochemical deposition so that electrical contacts can be easily formed on PS films. On the smooth bed of copper microcrystals, both center-hollowed and center-solid equilateral triangles are observed in the sizes of several micrometers.