1. Liu Y R, Wang Z X, Yu J L, Xu H H 2009 Acta Phys. Sin. 58 8566 (in Chinese) [刘玉荣, 王智欣, 虞佳乐, 徐海红 2009 物理学报 58 8556]
2. Yuan G C, Xu Z, Zhao S L, Zhang F J, Jiang W W, Huang J Z, Song D D, Zhu H N, Huang J Y, Xu S R 2008 Acta Phys. Sin. 57 5911 (in Chinese) [袁广才, 徐征, 赵谡玲, 张福俊, 姜薇薇, 黄金昭, 宋丹丹, 朱海娜, 黄金英, 徐叙瑢 2008 物理学报 57 5911]
3. Xu T Y, Wu H Z, Zhang Y Y, Wang X, Zhu X M, Yan Z J 2010 Acta Phys. Sin. 59 5018 (in Chinese) [徐天宇, 吴惠桢, 张莹莹, 王雄, 朱夏明, 原子健 2010 物理学报 59 5018]
4. Zhang L, Li J, Zhang X W, Jiang X Y, Zhang Z L 2009 Appl. Phys. Lett. 95 072112
5. Dehuff N L, Kettenring E S, Hong D, Chiang H Q, Wager J F 2005 J. Appl. Phys. 97 064505