STRUCTURE AND DYNAMICS OF DIAMOND(100) SURFACES AT HIGH HYDROGEN COVERAGE

The structural properties of hydrogenated diamond (100) surfaces have been investigated via a Tight-Binding model. For H coverages intermedi ate between the monohydrogenated and dihydrogenated surfaces, stable g eometries consisting of monohydrogenated dimer units and dihydride uni ts are found. When the H coverage is sufficiently high, the substrate lattice is found to distort in order to reduce steric repulsions betwe en the dihydride units. We thereby obtain a novel structure for the di hydrogenated surface which is significantly more stable than those pro posed previously. Tight-Binding Molecular Dynamics is used to illustra te a mechanism for the rapid removal of isolated monohydride units, wh ich are, therefore, suggested to be kinetically as well as thermodynam ically unstable.