1. School of Physical Science and Technology & Lanzhou Center for Theoretical Physics & Key Laboratory of Theoretical Physics of Gansu Province Lanzhou University Lanzhou 730000 China
2. State Key Laboratory of Applied Organic Chemistry (SKLAOC) College of Chemistry and Chemical Engineering Lanzhou University Lanzhou 730000 China
3. Department of Microelectronic Science and Engineering School of Physical Science and Technology Ningbo University Ningbo 315211 China
4. Center for Excellence in Nanoscience (CAS) Key Laboratory of Nanosystem and Hierarchical Fabrication (CAS) National Center for Nanoscience and Technology Beijing 100190 China