INTERFACE STRUCTURE AND OVERGROWTH ORIENTATION FOR NIOBIUM AND MOLYBDENUM FILMS ON SAPPHIRE SUBSTRATES .2. R-PLANE SUBSTRATES

We show that when niobium and molybdenum films are sputter deposited o n R-plane sapphire substrates, {001} growth is misoriented, and the an gle of misorientation is different for the two metals, being 2.6 degre es for niobium and 3.8 degrees for molybdenum. By characterizing the i nterface dislocation array in both systems, we show that the misorient ations can consistently be interpreted in relation to the differing no n-misfit-relieving Burgers vectors components of the geometrically nec essary misfit dislocation arrays present for the two systems. The way in which this indicates that the metal overgrowth immediately adjacent to the sapphire is perfectly oriented is discussed in relation to the interface-dominated mode of growth implied.