ATOMIC-STRUCTURE OF DISLOCATIONS IN SILICON, GERMANIUM AND DIAMOND

Atomic structures of perfect (90° and 60°) and partial (90°) dislocations including total and core energies have been calculated using four different interatomic potentials in silicon, germanium and diamond. The core energies of dislocations do not scale with the magnitudes of Burgers vectors associated with them. However, the energies of dislocations in the elastic region are found to be directly proportional to the square of the Burgers vector, as predicted by the theory of elasticity. The Stillinger-Weber (SW) and TersofT(T) potentials are more suitable for calculating the core structures with large distortions including the dangling bonds such as found in 60° dislocations. In the absence of dangling bonds, the core energies are highest for Keating (K) potentials, followed by T, SW and Baraff-Kane-Schluter (B) potentials (Si). The core energies calculated using B potentials are considerably lower as a result of much lower values for the bond-bending parameter. As an example, the core energies of a 90° ((a/2)[lI0](001)|[110]) dislocation in silicon are calculated to be 0·62 (K), 0·29 (B), 0·49 (SW) and 0·51 eV Å−1(T). The total energies are 2·04(K), 1.15(B), 1·64(SW) and l·73eV Å−l (T) at a radial distance of 28 Å from the dislocation line. A comparison of the potentials shows that the differences in the energy calculations by these potentials are mainly due to bond bending parameters. Internally consistant energy values of dislocations are presented and compared for explaining the reactions and growth directions of dislocations. © 1990 Taylor & Francis Group, LLC.