Epitaxial technology of Si/CoSi2/Si layers for solar cell application

High quality Si/CoSi₂/Si double heterostructures were developed using a conventional magnetron sputtering system. In this technique, CoSi₂ is etched away by hydrofluoric acid allowing the thin monocrystalline Si film to be separated from the supporting single crystal silicon substrate, which is reused many times. This process promises to allow fabrication of a new type of highly efficient large area thin film monocrystalline Si solar cell at low cost. The crystalline quality of the films was checked by transmission electron microscopy. We also studied the growth mechanism of epitaxial CoSi₂ and demonstrate that phase formation is controlled by diffusion of Co through the growing CoSi_x.