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

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