Application of tight-binding and path probability methods to the junction relaxation of semiconductor heterostructures

The atomistic and thermodynamic properties of semiconductor heterostructure s are investigated by using the tight-binding (TB) electronic theory and pa th probability method (PPM). The atomic diffusion in the semiconductor inte rface is studied via the vacancy mechanism of diffusion using the nonequili brium irreversible statistical mechanical approach, PPM. The effective pair interaction energies between the constituent atoms are derived by using th e zeros-poles method, taking into account the misfit strains at the interfa ce. We study the junction relaxation processes of semiconductor heterostruc tures such as SiGe/Si(001), GaAs/Si(001), and ZnSe/GaAs(001) systems. It ha s been found that the junction relaxation exhibits characteristic features, e.g., overshooting and uphill diffusion along the chemical potential gradi ent depending on the temperature and relative magnitude of effective pair i nteraction energies. It is also shown that, even for the very early stage o f the junction relaxation, the interface electronic properties are strongly influenced by the interface disorder.