1. Institute for Clean Energy and Advanced Materials, School of Materials and Energy, Southwest University, Chongqing 400715, P. R. China
2. Centre for Advanced Thin Films Materials and Devices, Southwest University, Chongqing 400715, P. R. China
3. Key Laboratory of Extraordinary Bond Engineering and Advance Materials Technology (EBEAM) of Chongqing, Yangtze Normal University, Chongqing 408100, P. R. China
4. School of Physics and Electronic Science, Zunyi Normal College, Zunyi 563002, P. R. China