1. M. Joseph, H. Tabata, T. Kawai, Jpn J. Appl. Phys., Part 1 38, L1205 (1999)
2. M. Venkatesan, C.B. Fitzgerald, J.G. Lunney, J.M.D. Coey, Phys. Rev. Lett. 93, 177206 (2004)
3. C. Klingshirn, H. Priller, M. Decker, J. Bruckner, H. Kalt, R. Hauschild, J. Zeller, A. Waag, A. Bakin, H. Wehmann, K. Thonke, R. Sauer, R. Kling, F. Reuss, C. Kirchner, Adv. Solid State Phys. 45, 275 (2005)
4. $\rm{\ddot{U}}$ . $\rm{\ddot{O}}$ zg $\rm{\ddot{u}}$ r, Y.I. Alivov, C. Liu, A. Teke, M.A. Reshchikov, S. Do $\rm{\breve{g}}$ an, V. Avrutin, S.-J. Cho, H. Morko $\rm{\breve{c}}$ , J. Appl. Phys. 98, 041301 (2005)
5. H.-J. Freund, Surf. Sci. 601, 1438 (2007)