1. E.F. Schubert, Light-Emitting Diodes (Cambridge University Press, New York, 2010)
2. Y. Yang, X.A. Cao, C.H. Yan, Appl. Phys. Lett. 94, 041117 (2009)
3. X.A. Cao, A. Teetsova, F. Shahedipour-Sandvikb, S.D. Arthura, J. Cryst. Growth 264, 172 (2004)
4. B. Monemar, B.E. Sernelius, Appl. Phys. Lett. 91, 181103 (2007)
5. S. Choi, H.J. Kim, S.-S. Kim, J. Liu, J. Kim, J.-H. Ryou, R.D. Dupuis, A.M. Fischer, F.A. Ponce, Appl. Phys. Lett. 96, 221105 (2010)