Core structure of the Lomer dislocation in germanium and silicon

Abstract

The core structure of the Lomer dislocation has been determined by high-resolution transmission electron microscopy at the 2.5 Å level. In addition to the Hornstra model without dangling bonds, a new core model containing one pair of atoms in a stacking-fault position is proposed. This form is stabilized either by a small amount of impurity in the core or by core reconstruction. It. is inferred from these observations that the Lomer-Cottrell lock is not the lowest energy state of a Lomer dislocation. From a comparison between experimentally deduced atomic positions around the core, and those calculated by elasticity theory, a 6 Å core radius is determined.