Examples of other diffusion barriers suitable for use in the present invention besides Ni include Cr, Pd, Fe, and other metals, thickness of a few thousand Angstroms to several microns, with a lattice structure different from the superlattice materials. [0069] The thickness of various ohmic metallizations of the present invention can be Cr/Au/Ni/Au of 300 ???/3000 ???/300 ???/3000 ??? and Ni/Au of