Abstract: A structure is fabricated comprising a substrate, a dielectric layer formed over the substrate, and a single crystal layer of a compound formed over the dielectric layer. The single crystal layer is formed by the chemical reaction of at least a first element with an initial single crystal layer of a second element on the dielectric layer having an initial thickness of about 100 to about 10,000 angstroms.According to another aspect, a carbide single crystal layer is provided on a substrate by depositing carbon from a solid carbon source at a low rate and low temperature, followed by reacting the carbon with the underlying layer to convert it to the carbide.