1. School of Electrical and Computer Engineering; RMIT University; Melbourne VIC 3001 Australia
2. ARC Centre of Excellence for Ultrahigh Bandwidth Devices and Optical Systems; RMIT University; VIC 3001 Melbourne Australia
3. Micro/Nanophysics Research Laboratory; RMIT University; Melbourne VIC 3001 Australia
4. School of Aerospace, Mechanical and Manufacturing Engineering; RMIT University; VIC 3001 Melbourne Australia
5. Institut d'Electronique; de Micréoelectronique et de Nanotechnologie (IEMN); UMR CNRS 8520, Université de Lille 1 59655 Villeneuve d'Ascq Cedex France