[Dai, Zhiping] Hengyang Normal Univ, Dept Phys & Elect Informat Sci, Hengyang 421002, Peoples R China.^[Yang, Zhenfeng] Hebei Univ Sci & Technol, Sch Econ & Management, Shijiazhuang 050018, Peoples R China.^[Yang, Zhenjun;Pang, Zhaoguang;Zhang, Shumin] Hebei Normal Univ, Hebei Adv Thin Films Lab, Coll Phys & Informat Engn, Shijiazhuang 050024, Peoples R China.