Abstract: A method for generating repeatable and reproducible crystallographic grain-boundary junctions is provided by forming a film on a crystalline substrate which has intersecting faces. In a preferred embodiment, a single crystal substrate is etched by an anisotropic etchant to provide a "V"-groove in one face, and an epitaxial superconducting film is grown on the faces of the V-groove. In another preferred embodiment, a step is etched with an anisotropic etch, and an epitaxial superconducting film grown on the step. Grain-boundary junctions are formed at the points of intersection of the faces with each other, or with the faces and the surface of the substrate. The film may be patterned and etched in the area of the boundary junction to form useful devices.