Institute of Microstructure and Properties of Advanced Materials;
Beijing University of Technology;
Beijing 100124;
China;
School of Physics and Microelectronics;
and National Key Laboratory of Crystal Materials;
Shandong University;
Jinan 250100;
China;
School of Information Science and Engineering;
and National Key Laboratory of Crystal Materials;
Shandong University;
Jinan 250100;
China;