Towards experimental identification of vacancy complexes in InN

In this contribution we present ab-initio calculations of positron states and annihilation at vacancies and vacancy complexes in InN. Momentum distributions of annihilating electron-positron pairs in indium (V(In)) and nitrogen vacancies (V(N)) as well as mixed vacancy clusters are calculated. Based on the modelled data the possibility of their experimental detection and distinction using positron annihilation spectroscopy is discussed. No localization of the positron density is found for isolated V(N) and V(N) clusters of up to 4V(N). On the other hand, V(In) and mixed vacancy clusters asct as efficient positron traps in InN While the calculated momentum distributions for the divacancy and V(In) are quiet close mixed vacancy clusters which contain one V(In) and two or more V(N) show well distinct spectra, that could be distinguished in suitable positron annihilation experiments. (C) 2011 WILEY-VCH Verlag Gmbh & Co. KGaA, Weinheim