AbstractWe describe our efforts to control the grain boundary alignment in polycrystalline thin films of silicon by using a biaxially textured template layer of CaF₂ for photovoltaic device applications. We have chosen CaF2 as a candidate material due to its close lattice match with silicon and its suitability as an ion beam assisted deposition (IBAD) material. We show that the CaF₂ aligns biaxially at a thickness of ~10 nm and, with the addition of an epitaxial CaF₂ layer, has an in-plane texture of ~15°. Deposition of a subsequent layer of Si aligns on the template layer with an in-plane texture of 10.8°. The additional improvement of in-plane texture is similar to the behavior observed in more fully characterized IBAD materials systems. A germanium buffer layer is used to assist in the epitaxial deposition of Si on CaF₂ template layers and single crystal substrates. These experiments confirm that an IBAD template can be used to biaxially orient polycrystalline Si.