Anodizing method yielding multiple porous seed layers for the epitaxial growth of monocrystalline Si films

This paper reports on recent improvements in the fabrication of 5 to 15-mu m-thick self-standing porous Si seed films for monocrystalline epitaxy. A multiple three-step anodizing method allows us to separate multiple self-standing porous films from a single 4-in. Si wafer with only one mounting step. So far, we have separated up to three self-standing porous films with diameters of 85 mm (limited by our etch setup) with one continuous anodizing process. The porous films are used as seeding layers for monocrystalline Si epitaxy. Solar cells fabricated from 38-mu m-thick monocrystalline silicon films show independently confirmed efficiencies up to 13.6%. (c) 2006 The Electrochemical Society.