1. Department of Microelectronic Science and Engineering School of Physical Science and Technology Ningbo University Zhejiang 315211 P. R. China
2. School of Optoelectronic Science and Engineering The State Key Laboratory of Electronic Thin Films and Integrated Devices University of Electronic Science and Technology of China (UESTC) Chengdu 611731 P. R. China
3. College of Optical and Electronic Technology China Jiliang University Hangzhou 310018 P. R. China