1. Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of China Chengdu 610054 Sichuan China
2. Department of Electrical and Computer Engineering University of Houston Houston TX 77204 USA
3. Department of Materials Science and Engineering University of Houston Houston TX 77204 USA
4. Department of Electrical and Computer Engineering Baylor University Waco TX 76798 USA
5. School of Optical and Electronic Information Huazhong University of Science and Technology Wuhan 430074 Hubei China
6. Department of Civil and Environmental Engineering University of Houston Houston TX 77204 USA
7. Key Laboratory of Graphene Technologies and Applications of Zhejiang Province Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences Ningbo 315201 Zhejiang China