1. Department of Electrical and Computer Engineering; School of Engineering; Nazarbayev University; Astana 010000 Kazakhstan
2. Department of Electronic and Information Engineering; The Hong Kong Polytechnic University; Hong Kong S.A.R.
3. Department of Physics; Hong Kong Baptist University; Hong Kong S.A.R.
4. Department of Materials Science and Engineering; University of California; Los Angeles CA 90095-9000 USA
5. Department of Physics; The University of Hong Kong; Pokfulam Hong Kong S.A.R.
6. School of Engineering; Nazarbayev University; Astana Kazakhstan