[1] [1] Najafabadi E, Knauer K A, Haske W, et al. Appl. Phys. Lett., 2012, 101: 023304.

[3] [3] Tae J P, Woo S J, Park J J, et al. Appl. Phys. Lett., 2008, 92(11): 113308-1.

[5] [5] Liu Z W, Helander M G, Wang Z B, et, al. Appl. Phys. Lett., 2009, 94: 113305.

[6] [6] Adachi C, Baldo M A, Forrest S R, et al. Appl. Phys. Lett., 2000, 77(6): 904.

[9] [9] Han Liangliang, Yang Dongfang, Li Wenlian, et al. Appl. Phys. Lett., 2008, 93: 153303.

[13] [13] Zhao Yongbiao, Chen Jiangshan, Ma Dongge. Appl. Phys. Lett., 2011, 99: 163.

[14] [14] Zhao Yan, Duan Lian, Zhang Deqiang, et al. Appl. Phys. Lett., 2012, 100: 083304.

[15] [15] Teng Mingyu, Zhang Song, Jiang Shengwei, et al. Appl. Phys. Lett., 2012, 100: 0703303.