In-grown group III (cation) vacancies (VGa, VAl, VIn) in GaN, AlN and InN tend to be complexed with donor-type defects on the N sub-lattice, such as ON or the N vacancy (VN). The cation vacancies and their complexes were generally deep acceptors, and hence they compensated for the n-type conductivity and add to the scattering centers limiting the carrier mobility in these materials. This work presented results obtained with positron annihilation spectroscopy in a variety of GaN, AlN, InN samples from different sources. The vacancy-donor complexes were different in these three materials, and their importance in determining the opto-electronic properties of the material varied as well. The formation of these defects was discussed in the light of the differences in the growth methods.

On the Formation of Vacancy Defects in III-Nitride Semiconductors. F.Tuomisto, J.M.Mäki, C.Rauch, I.Makkonen: Journal of Crystal Growth, 2012, 350[1], 93-7