Electronic and structural properties of vacancy and self-interstitial defects in germanium

The electronic and structural properties of an isolated vacancy and self-in terstitial defects in germanium are studied through 'parameter free' calcul ations. We analyze the lattice relaxations and Jahn-Teller distortions for several charge states. Our results for ionization levels of the Ge-vacancy are in fair agreement with experimental results. In contrast to the silicon vacancy we obtain that the germanium vacancy does not present an Anderson negative-U. For the self-interstitial defect we obtain, similarly to silico n, that the lowest-energy configuration is the split dumbbell configuration . (C) 1999 Elsevier Science B.V. All rights reserved.