[1] Morkoc H, Strite S, Gao G B, Lin M E, Sverdlov B and Burns M 1994
J. Appl. Phys. 76 1363

[2] Vispute R D, Narayan J, Wu H and Jagannadham K 1995 J. Appl.
Phys. 77 4724

[3] Moore W J, Freitas J A, Holm R T, Kovalenkov O and Dmitriev V 2005
Appl. Phys. Lett. 86 141912

[4] Liu F S, Liu Q L, Liang J K, Luo J, Zhang H R, Zhang Y, Sun B J and
Rao G H 2006 J. Appl. Phys. 99 053515

[5] Chen S W, Lin H F, Sung T T, Wu J D, Kao H L and Chen J S 2003
Electron. Lett. 39 1691

[6] Ni X F, Zhu L P, Ye Z Z, Zhao Z, Tang H P, Hong W and Zhao B H 2005
Surface Coatings Technol. 198 350

[7] Hirato K, Fujioka H, Ito S, Ohta J and Oshima M 2003 Thin
Solid Films 435 131

[8] Kaya K, Takahashi H, Shibata Y, Kanno Y and Hirai1 T 1997 Jpn.
J. Appl. Phys. 36 2837

[9] Dovidenko K, Oktyabrsky S and Narayan J 1997 J. Appl. Phys.
82 4296

[10] Xi D J, Zheng Y D, Chen P, Zhao Z M, Chen P, Xie S Y, Jiang R L,
Shen B, Gu S L and Zhang R 2002 Chin. Phys. Lett. 19 543

[11] Torres V M, Edwards J L, Wilkens B J, Smith D J, Doak R B and
Tsong I S T 1999 Appl. Phys. Lett. 74 985

[12] Onojima N, Suda J and Matsunami H 2002 Appl. Phys. Lett.
80 76

[13] Lin W T, Meng L C, Chen G J and Liu H S 1995 Appl. Phys.
Lett. 66 2066

[14] Gyorgy E, Ristoscu C, Mihailescu I N, Klini A, Vainos N, Fotakis
C, Ghica C, Schmerber G and Faerber J 2001 J. Appl. Phys.
90 456

[15] Ristoscu C, Ducu C, Socol G, Craciunoiu F and Mihailescu I N 2005
Appl. Surf. Sci. 248 411

[16] Ito S, Fujioka H, Ohta J, Takahashi H and Oshima M 2003 Thin
Solid Films 435 215

[17] Okamoto K, Inoue S, Matsuki N, Kim T W, Fujioka H and Oshima M
2005 Phys. Status Solidi A 202 R149

[18] Inoue S, Okamoto K, Matsuki N, Kim T W and Fujioka H 2006 J.
Crystal Growth 289 574

[19] Cullity B 1955 Elements of X-ray Diffraction (London:
Addison-Wesley) chap 3