Mechanical and Electronic Properties of Strained Layer Superlattices Studied by Density Functional TB and Path Probability Methods

The atomic and electronic structures of semiconductor heterostructures including steps, misfit dislocations and interface disorder are studied by using the densityfunctional tight-binding (TB) method. Atomic structures of misfit dislocations both edge type 1/2 <110> (001) and 60°dislocations in the semiconductor heterostructures, like Si-Ge superlattices and GaAs/Si systems are studied by using order of N [O(N)] calculational method. The path probability method (PPM) in the statistical physics is used to study the influence of the interface disorder on the electronic properties of the semiconductor heterostructures. The fracture behavior of semiconductor heterostructures under applied stress is also investigated and debonding mechanism between the two different semiconductor layers is discussed. It is shown that the junction relaxation influences quite significantly on the electronic and mechanical properties of semiconductor heterostructures. keywords: density-functional TB method, superlattice, orbital peeling method, semiconductor heterostructure, path probability method (PPM).