Tight-binding and local density approximation studies of semiconductor surfaces and small organic adsorbates

The structure of the GaAs(001)-(2x4) surface has been the subject of considerable controversy. We have fitted tight-binding parameters to local density approximation (LDA) results. Using a linear scaling right-binding method we have been able to model sufficiently large unit cells to investigate the energetics of dimer row kinking, which provides strong evidence to support the identification of the beta phase with the trench dimer model. Having done so, we returned to LDA calculations to investigate the interaction of the important chemical beam epitaxial growth precursor tri-methyl-gallium with the surface, in order to identify both the mobile precursor structure and the final bonded structure.