1. Solid State Physics, Lund University, Box 118, S-221 00, Lund, Sweden, Microtechnology and Nanoscience, Chalmers University of Technology, S-412 96, Göteborg, Sweden, School of Physical Sciences, The University of Queensland, St. Lucia, 4072 Australia, and Polymer and Materials Chemistry/nCHREM, Lund University, Box 124, S-221 00, Lund, Sweden