1. Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis, #08-03 Singapore 138634, Singapore
2. Department of Materials, Royal School of Mines, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
3. Faculty of Science, Agriculture, & Engineering, Newcastle University in Singapore, Singapore 567739, Singapore
4. Department of Materials Science and Engineering, National University of Singapore (NUS), 9 Engineering Drive 1, #03-09 EA, Singapore 117575, Singapore
5. Department of Electronic Engineering, The Chinese University of Hong Kong, New Territories, Hong Kong SAR 999077, China