High-quality GaN on intentionally roughened c-sapphire Y. Golan, P. Fini, D. Dahan, F. Wu, S. Zamir, J. Salzman and J. S. Speck Eur. Phys. J. AP, 22 1 (2003) 11-14 Published online: 25 February 2003 DOI: 10.1051/epjap:2003012