Macro- and micro-strain in GaN nanowires on Si(111)
  We analyze the strain state of GaN nanowire ensembles by x-ray diffraction. The nanowires are grown by molecular beam epitaxy on a Si(111) substrate in a self-organized manner. On a macroscopic scale, the nanowires are found to be free of strain. However, coalescence of the nanowires results in micro-strain with a magnitude from +-0.015% to +-0.03%.This micro-strain contributes to the linewidth observed in low-temperature photoluminescence spectra. 
Bernd Jenichen, Oliver Brandt, Carsten Pfueller, Pinar Dogan, Mathias   Knelangen, Achim Trampert
cond-mat.mes-hall