1. Microelectronics and Materials Physics Laboratories, Department of Electrical and Information Engineering, and EMPART Research Group of Infotech, University of Oulu, P.O. Box 4500, Oulu FIN-90014, Finland, Department of Materials Science & Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180, Department of Mechanical Engineering and Materials Science, Rice University, Houston, Texas 77251-1892, and Rensselaer Nanotechnology Center, Rensselaer Polytechnic Institute, Troy, New York 12180