1. Department of Electrical Engineering and Computer Science, York University, 4700 Keele Street, Toronto, Ontario M3J 1P3, Canada
2. Department of Physics and Astronomy, York University, 4700 Keele Street, Toronto, Ontario M3J 1P3, Canada
3. Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, Dresden 01328, Germany
4. Institute of Physics, Technische Universität Chemnitz, Reichenhainer Straße 70, Chemnitz 09126, Germany