[1] Kobayashi S and Tanaka S 1996 SID J. 4 157

[2] Yang S, Stoffers S and Zhang F et. al. 1998 Appl.
Phys. Lett. 72 158

[3] Wang D J, Wang J L and Li L 2006 Chin. Phys. Lett.
23 2247

[4] Flynn M and Kitai A H 2001 J. Electrochem. Soc.
148 H149

[5] Minami T, Maeno T, Kuroi Y and Takata S 1995 Jpn. J.
Appl. Phys. 34 L684

[6] Kang Y C et al. 2000 Mater. Res. Bull. 35 789

[7] Choe J Y et al 2001 J. Lumin. 93 119

[8] Ravichandran D et al 1997 J. Lumin. 71 291

[9] Zhou Y H et al. 2002 Opti. Mater. 20 13

[10] Mathur S et al 2005 Mater. Res. Bull. 40
439

[11] Heer S et al 2001 Chem. Phys. Lett. 334 293

[12] Heer S et al 2001 J. Lumin. 94-95 337

[13] Yamagab M et al 1988 J. Lumin. 39 335

[14] Binnemans K and G\"{orller-Walrand C 1997 J. Phys.:
Condens. Matter 9 1637

[15] Zhu N F et al 2007 J. Lumin. 122-123 704

[16] Yu M et al 2003 Chem. Phys. Lett. 371 183

[17] Jung K Y and Lee H W 2007 J. Lumin. 126 469

[18] Jia D et al 2003 J. Appl. Phys. 93 148

[19] Dexter D L 1953 J. Chem. Phys. 21 836

[20] Nikl M et al 2005 J. Phys.: Condens. Matter.
17 3367

[21] Setlur A A and Srivastava A M 2006 Opt. Mater.
29 410

[22]Srivastava A M 2002 Mater. Res. Bull. 37 745

[23] Kiliaan H S and Blasse G 1987 Mater. Chem. Phys.
18 155

[24] van de Craats A M and Blasse G 1995 Chem. Phys.
Lett. 243 559

[25] Zorenko Y et al 2007 Radiat. Meas. 42 882

[26] Antic-Fidancev E et al 2001 Phys. Rev. B 64
195108

[27] Srivastava A M and Beers W W 1999 J. Lumin.
81 293

[28] Srivastava A M et al 1990 J. Electrochem. Soc.
137 2959

[29] Mo L Y et al 1985 J. Electrochem. Soc. 132
717