Native defects in germanium

We study, using first principles calculations, the electronic and structura l properties of an isolated vacancy and self-interstitial defects in german ium. For the vacancy we analyze the lattice relaxations for the charge stat es (+ +), (+), and (0), and show that the atomic displacements, albeit smal l, are not completely negligible for the second-nearest-neighbor atoms to t he vacancy site. Moreover, we show that the relaxations decay slowly along the zigzags that go through the vacancy site. For the self-interstitial we present an analysis of the charge density, which supports the description o f this defect as a four-atoms ring strongly attached to the lattice, which we have named a kite-defect (C) 2001 Elsevier Science B.V. All rights reser ved.