An ab initio atomistic study of the effects of nitrogen vacancies both in InN bulk and at (1¯1•0) non-polar surface was presented and it was confirmed that these defects acted as n-type impurities. Based upon the dependence of the vacancy formation energy upon the distance from the surface, it was predicted that, at thermodynamic equilibrium, these defects tended to segregate in the outermost surface layers reaching a concentration which was few orders of magnitude higher than in the bulk phase. Considering out-of-equilibrium growth and in view of the large calculated energy barrier that characterize vacancy diffusion, it was also predicted that the N enriched layer would extend hundreds of angstroms from the surface for typical growth processes. This vacancy accumulation at surfaces was consistent with the observed high electron accumulation layer.

Nitrogen Vacancies at InN (1¯100) Surfaces - a Theoretical Study. A.Terentjevs, A.Catellani, G.Cicero: Applied Physics Letters, 2010, 96[17], 171901