SEMICONDUCTOR SURFACE AND INTERFACE DYNAMICS FROM TIGHT-BINDING MOLECULAR-DYNAMICS SIMULATIONS

Tight-binding molecular dynamics simulations have been performed to compute the bulk, (110) surface, and (110)-p(1 X 1)-Sb(1 ML) interfacial atomic vibrational spectra for GaAs and InP. The same tight-binding total energy model that successfully described the static surface and interfacial atomic and electronic structure for these systems is utilized in the molecular dynamics simulations. The results for the bulk vibrational energies are in semiquantitative agreement with experimental results, displaying approximately the same level of variance as other model computations. Moreover, these simulations are used to examine the effects of anharmonicity in the system by investigating the temperature dependence of the vibrational spectra. The (110) surface vibrational energies are in quantitative agreement with the scattering data, and a comparison of the results for GaAs (110) and InP (110) supports the existance of a surface vibrational mode that is characteristic of the relaxed (110) surface, and whose energy is similar for each zinc blende (110) surface. Last, the computed vibrational energies for the III-V(110)-p(1 X 1)-Sb(1 ML) interface are in semiquantitative agreement with Raman scattering data and illustrate the effects of the overlayer binding on the surface vibrational spectrum.