GaN nanowires were grown without any catalyst by plasma-assisted molecular beam
epitaxy. Under supply of Mg, nanowire nucleation is faster, the areal density of
wires increases to a higher value, and nanowire coalescence is more pronounced
than without Mg. During nanowire nucleation the Ga desorption was monitored insitu
by line-of-sight quadrupolemass spectrometry for various substrate temperatures.
Nucleation energies of 4.0±0.3 eV and 3.2±0.3 eV without and with Mg supply were
deduced, respectively. This effect has to be taken into account for the fabrication of
nanowire devices and could be employed to tune the NW areal density
