Review of layer transfer processes for crystalline thin-film silicon solarcells

Layer transfer processes provide a new and largely unexplored route for the fabrication of highly efficient monocrystalline thin-film Si solar cells. Monocrystalline Si wafers serve as a substrate for epitaxial growth. A spec ial surface conditioning of the substrate permits the transfer of a thin ep itaxial film to an arbitrary carrier substrate. The growth substrate is the n re-used to fabricate further cells. The possibility to use different mate rials for growing the thin film and for carrying the devices broadens the d esign flexibility and opens a new path for cost reduction. We describe and discuss the various layer transfer processes that are currently being devel oped for Si. A particular important point to work on in the future is the d emonstration of a frequent re-use of the substrate and the development of a large-area and low-cost epitaxy technique.