Affiliation: | 1. Dept. of Physics, Imperial College London, South Kensington, London, SW7 2AZ, UK;2. Institute of Materials Research and Engineering, A*STAR, 3 Research Link, Singapore 117602, Singapore;3. Sch. of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore;4. Dept. of Materials, Imperial College London, South Kensington, London, SW7 2AZ, UK |