NOVELTY - A photovoltaic device comprises a metal substrate (14) with a crystalline orientation comprising a diffracting structure integrated into a surface of the metal substrate; a heteroepitaxial crystal silicon layer (12) having the crystalline orientation of the substrate; and a heteroepitaxially grown buffer layer (16) having the crystalline orientation. The buffer layer is positioned adjacent to the surface of the metal substrate having the diffracting structure.    USE - A photovoltaic device.    ADVANTAGE - Back-surface reflectivity is improved, increasing light-trapping properties and, thus, enhancing efficiency of crystal oriented photovoltaic cells.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) solar cell comprising a nickel tungsten substrate, a heteroepitaxially grown buffer layer, a metal layer which is positioned between the buffer layer and the substrate and which comprises a metal having a higher reflectivity than nickel; and a heteroepitaxial crystal silicon layer; and    (2) method for increasing back surface reflectivity of a photovoltaic cell comprising forming approximately 2-10 nm reflective layer over a metal substrate, in which the reflective layer has a higher reflectivity than the metal of the substrate; heteroepitaxially growing a buffer layer and a crystal silicon layer, where each of the metal substrate, buffer layer and crystal silicon layer has a common crystal orientation.    The metal layer comprises at least one of gold, silver, aluminum, copper, and rhodium. The buffer layer comprises magnesium oxide and aluminum oxide. The buffer layer comprises conductive pathways to provide electron or hole migration from the silicon layer to the nickel tungsten substrate.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional view of a crystal silicon structure heteroepitaxially grown over a buffer covered metal substrate.    Photovoltaic cell (10)    Crystal silicon layer (12)    Metal substrate (14)    Buffer layer (16)    Highly doped layer (18)