Fracture Processes in Silicon

Three different approaches have been tried. One approach includes very accurate first-principles methods which are however applicable to small systems containing few tens of atoms. A second approach comprises methods of simulations based on interatomic potentials, which can be easily applied to systems containing 10 atoms or more, but has serious problems with accuracy that can led to qualitatively wrong results. The third approach combines the previous two using an accurate method near the tip of the crack, and an interatomic potential far from the crack. 

Silicon is a suitable material for study of the perfectly brittle failure. 

Two important conclusions may be drawn from the Griffith criterion (14.1) 

A perfectly brittle crack in a crystal is therefore expected to choose a cleavage plane with low surface energy and propagate on this plane with equal ease in all directions. 

The ab initio methods make it possible for one to analyze in detail the bondingbreaking process at crack tip in silicon. These methods can accurately describe the nonlinear forces acting on atoms at the crack tip. 

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