Stability, reconstruction, and electronic properties of diamond (100) and (111) surfaces

Abstract

Results of scanning-tunneling-microscopy (STM) and molecular-dynamics (MD) annealing studies based on quantum-mechanically derived interatomic forces using a semiempirical density-functional approach are combined for analyzing diamond surface structures. Experimentally obtained STM images of diamond (100) and (111) faces on polycrystalline films reveal (1×1),(√3 × √3 ) R30°, and possible (2×1) structures. The (100) faces show stable (2×1) reconstruction with dimer formation. Surface structures with and without adsorbed hydrogen are determined and their stability is obtained by MD simulated annealing techniques. The bulklike and (√3 × √3 ) R30° structures, as they are observed on grown (111) facets, are attributed to the two different single atomic (111) layers, which support growth mechanisms, in which the two alternating single atomic layers grow in turn and not simultaneously. The equilibrium surface modifications which have been realized are electronically characterized by investigating the local electronic density of states at selected surface atoms. This information is compared and related to the features seen in the STM images.