Isovalent impurity-vacancy complexes in germanium

Electronic structure simulations are used to predict the structures and relative energies of clusters formed between isovalent impurities and lattice vacancies in germanium and for comparison in silicon. The structures and relative energies of a series of different carbon-vacancy complexes in germanium are considered. The technique is also used to predict the effect of carbon atoms on the binding of tin-vacancy pairs in germanium. For germanium and silicon different configurations containing carbon, tin and vacancies are stable. The calculations highlight important differences in the stability of clusters in germanium compared to silicon.