[1] H. Lu, W. J. Schaff, L. F. Eastman, and C. E. Stutz, Appl.
Phys. Lett. 82, 1736 (2003).
[2] I. Mahboob et al., Phys. Rev. Lett. 92, 036804 (2004).
[3] R. E. Jones et al., Phys. Rev. Lett. 96, 125505 (2006).
[4] K. M. Tracy, W. J. Mecouch, R. F. Davis, and R. J. Nemanich,
J. Appl. Phys. 94, 3163 (2003).
[5] T. D. Veal et al., Appl. Phys. Lett. 89, 202110 (2006).
[6] P. D. C. King et al., Phys. Rev. B 75, 115312 (2007).
[7] H. Lu et al., Mater. Res. Soc. Symp. Proc. 743, 317
(2003).
[8] W. J. Schaff et al., in: Nitride and Wide Bandgap Semiconductors
for Sensors, Photonics, and Electronics V, edited
by H. M. Ng and A. G. Baca, The Electrochemical
Society Proceedings Series, Vol. 2004-06 (Electrochemical
Society, Pennington, NJ, 2004), pp. 358–371.
[9] S. A. Chambers, T. Droubay, T. C. Kaspar, and M. Gutowski,
J. Vac. Sci. Technol. B 22, 2205 (2004).
[10] W. Mönch, Semiconductor surfaces and interfaces (Springer,
Berlin, 2001).
[11] I. Mahboob et al., Phys. Rev. B 69, 201307(R) (2004).
[12] P. D. C. King et al., Phys. Rev. B 77, 045316 (2008).
[13] C. G. Van de Walle and D. Segev, J. Appl. Phys. 101,
081704 (2007).