State Key Laboratory of Integrated Optoelectronics;
College of Electronic Science and Engineering;
Jilin University;
Changchun 130012;
China;
Nanotechnology Facility;
Swinburne University of Technology;
John St.;
Hawthorn 3122 Vic;
Australia;
State Key Laboratory of Precision Measurement Technology and Instruments;
Department of Precision Instrument;
Tsinghua University;
Beijing 100084;
China;