Department of Physics and Electronic Engineering, Handan College, Handan 056005;
Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, PO Box 912, Beijing 100083;
Department of Physics and Electronic Engineering, Handan College, Handan 056005;
Department of Physics and Electronic Engineering, Handan College, Handan 056005;
Department of Physics and Electronic Engineering, Handan College, Handan 056005;
Department of Physics and Electronic Engineering, Handan College, Handan 056005;
Department of Physics and Electronic Engineering, Handan College, Handan 056005;
Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, PO Box 912, Beijing 100083;