A device structure for thin, light trapped epitaxial silicon solar cells

Thin silicon solar cell device performance is particularly sensitive to electrical and optical quality at the back of the active device. The device back surface must be both well passivated and highly reflective. Achieving both of these device goals is difficult with conventional thin layer epitaxial growth techniques, which require substrate thinning to incorporate an appropriate back surface structure. In this work, epitaxial lateral overgrowth has been used to produce thin crystalline silicon device structures on silicon substrates. This technique allows the growth of epitaxial layers over dielectric films, which addresses back surface optical and electrical requirements. This structure is also mechanically stable, since substrate thinning is not required. Thin epitaxial structures demonstrating enhanced absorption have been produced. These layers are continuous over 99% of the growth area, and are less than 30 /spl mu/m thick.