1. State Key Laboratory on Integrated Optoelectronics, College
of Electronic Science and Engineering, Jilin University, Changchun 130012, P.R. China
2. State Key Laboratory
of Transducer Technology, Chinese Academy of Science, Changchun 130012, P.R. China
3. Institute of Physical
Chemistry, University of Tuebingen, 72076 Tuebingen, Germany