A superconductor device includes a barrier layer over a substrate including silicon, the barrier layer including silicon and nitrogen, and a seed layer for a superconductor layer over the barrier layer, the seed layer including aluminum and nitrogen, and superconductor layer over the seed layer, the superconductor layer including a layer of a superconductor material, the barrier layer serving as an oxidation barrier between the layer superconductor material and the substrate. In some embodiments, the superconductor device includes a waveguide and a metal contact at a sufficient distance from the waveguide to prevent optical coupling between the metal contact and the waveguide.