[1] Qingdao Univ, Coll Elect & Informat, Qingdao 266071, Peoples R China
[2] Univ Hlth & Rehabil Sci, Sch Rehabil Sci & Engn, Qingdao 266113, Peoples R China
[3] Korea Adv Nano Fab Ctr KANC, Dept thin film, Suwon 443270, South Korea
[4] Shandong Univ, Sch Microelect, Jinan 250101, Peoples R China