Thin monocrystalline silicon films for solar cells

Thin film monocrystalline silicon solar cells based on porous silicon layer transfer processes could be cost-effective because of their lower consumption of material use and the potential for high efficiency. Novel techniques of porous silicon film separation, obtained by anodization of silicon, are presented. Anodization techniques for porous silicon film separation are classified as either one-step or two-step. Two-step anodization provides better control over the one-step method in terms of porous silicon film thickness that can be separated. The substrate reusability of both the techniques is assessed through roughness measurements. A monocrystalline epitaxial layer is deposited on annealed porous silicon, and is then used to make a solar cell. A cell of 12% efficiency is realized in 18 /spl mu/m thick epitaxial layer with an excellent short circuit current of 32.9 mA/cm/sup 2/.