The results of ab initio molecular dynamics simulations of impurity-induced disordering in superlattices were presented. Two typical impurities, the Zn acceptor and the Si donor, were studied. It was found that Zn-induced interdiffusion was due to the formation of non-equilibrium group-III interstitials during Zn in-diffusion. The interstitials, which were bound to Zn acceptors via Coulomb forces, disordered the superlattice via kick-out processes on the group-III sub-lattice. On the other hand, Si-induced interdiffusion occurred via SiGa-VGa pairs. Their motion, via second-nearest neighbor jumps, disordered the group-III sub-lattice. The calculated activation energies for these processes were in good agreement with experiment.

J.Bernholc, B.Chen, Q.Zhang, C.Wang, B.Yakobson: Materials Science Forum, 1994, 143-147, 593-8