1. Henan Key Laboratory of Diamond Optoelectronic Materials and Devices Key Laboratory of Material Physics Ministry of Education School of Physics and Laboratory of Zhongyuan Light Zhengzhou University Zhengzhou 450052 China
2. School of Electronics and Information Zhengzhou University of Light Industry Zhengzhou 450002 China
3. Key Laboratory of Artificial Micro‐ and Nano‐Structures of Ministry of Education School of Physics and Technology Wuhan University Wuhan 430072 China