New conditions for one-step ELO were implemented to grow coalesced (11▪0) non-polar and (11▪2) semi-polar GaN layers starting, respectively, from R - and M -plane sapphire. A great part of the stacking faults and dislocations were filtrated resulting in GaN material with better structural and optical properties. In the ELO-like (11▪0) and (11▪2) films, the near band edge emission dominates photoluminescence spectra and was in the range of 3.45 to 3.48eV depending upon lattice deformation. The strongest emission was met for the semi-polar (11▪2) ELO. When mask stripes were not normal to the c-axis, a singular ELO was developed with inclined coalescence facets. However, in this case, stacking faults overgrew above the mask and so led to poor optical properties, dominated by stacking fault and dislocation-related peaks. In any case, the internal electric field reduction in (Al,Ga)N/GaN non- or semi-polar quantum-wells stacks was better viewed when the heterostructures were grown on ELO with stripes normal to the c-axis.

Reduction of Stacking Faults in (11▪0) and (11▪2) GaN Films by ELO Techniques and Benefit on GaN Wells Emission. Z.Bougrioua, M.Laügt, P.Vennéguès, I.Cestier, T.Gühne, E.Frayssinet, P.Gibart, M.Leroux: Physica Status Solidi A 2007, 204[1], 282-9