The effect of Mg doping upon the properties of GaN nanowires grown by plasma-assisted molecular beam epitaxy was studied. The most significant features were triple-twin domains; the density of which increased with increasing Mg content. The resultant high concentration of misplaced atoms gave rise to local changes in the crystal structure which were equivalent to the insertion of 3 non-relaxed zincblende atomic cells. This resulted in quantum wells along the wurtzite nanowire growth-axis. High-resolution electron energy-loss spectra were obtained exactly on the twinned (zincblende) and wurtzite planes. These atomic-resolution measurements permitted the identification of modifications in the local density of states and revealed changes in the band-to-band electronic transition energy from 3.4eV for wurtzite to 3.2eV in the twinned lattice regions. These results were in good agreement with ab initio atomistic simulations.

Triple-Twin Domains in Mg Doped GaN Wurtzite Nanowires: Structural and Electronic Properties of this Zinc-Blende-Like Stacking. J.Arbiol, S.Estradé, J.D.Prades, A.Cirera, F.Furtmayr, C.Stark, A.Laufer, M.Stutzmann, M.Eickhoff, M.H.Gass, A.L.Bleloch, F.Peiró, J.R.Morante: Nanotechnology, 2009, 20[14], 145704