Reduction of stacking faults in (11$ \bar 2 $0) and (11$ \bar 2 $2) GaN films by ELO techniques and benefit on GaN wells emission

Abstract

Abstract New conditions for one‐step ELO were implemented to grow coalesced (11 $ \bar 2 $ 0) non‐polar and (11 $ \bar 2 $ 2) semi‐polar GaN layers starting, respectively, from R ‐ and M ‐plane sapphire. A great part of the stacking faults (SFs) and dislocations are filtrated resulting in GaN material with better structural and optical properties. In the ELO‐like (11 $ \bar 2 $ 0) and (11 $ \bar 2 $ 2) films, the near band edge emission dominates photoluminescence spectra and is in the range 3.45–3.48 eV depending on lattice deformation. The strongest emission is met for the semi‐polar (11 $ \bar 2 $ 2) ELO. When mask stripes are not normal to the c ‐axis, a singular ELO is developed with inclined coalescence facets. However, in this case, SFs overgrow above the mask and so lead to poor optical properties, dominated by SF and dislocation related peaks. In any case, the internal electric field reduction in (Al,Ga)N/GaN non‐ or semi‐polar quantum‐wells stacks is better viewed when the heterostructures are grown on ELO with stripes normal to the c ‐axis. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)