Abstract

The atomistic configurations and electronic states of extended lattice defects (dislocations and grain boundaries) in diamond crystals are investigated in conjunction with their mechanical properties by using the tight-binding (TB) recursion electronic theory. It is shown that the atomic configurations and electronic states of mobile dislocations (30° and 90° partial of 1/2<110> {111} lattice dislocation) are similar in nature to those of Si crystals. However, it has been found that the cleavage strength of the grain boundaries in diamond is only slightly reduced ( ~10%) with respect to those of the single crystals; the amount of the reduction is considerably smaller than that of Si crystals.