New extended point defect structure in diamond cubic crystals

In the course of atomistic simulations of the dislocation array at the Ge/Si(001) interface, we have generated a new closed symmetric defect structure comprising eighteen atoms that may be found in a variety of circumstances including dislocation intersections and grain boundaries. The structure maintains tetrahedral bonding with reasonable changes in bond lengths and angles, and may have interesting electronic properties. At the Ge/Si interface, these extended point defects may reach a very high planar concentration of {~}10¹²/cm².