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

The structure of the GaAs(001)-(2 × 4) surface has been the subject of considerable controversy. We have fitted tight-binding parameters to local density approximation (LDA) results. Using a linear scaling tight-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 β 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.