Atomic structure of GaAs(100)‐(2×1) and (2×4) reconstructed surfaces

摘要: Structural models for the Ga (or Al)‐rich GaAs(100)‐(2×1) surface and As‐rich (2×4) are examined by tight‐binding based total‐energy calculations. The most stable (2×1) contains 1/2 monolayer of vacancies which make nonmetallic nonpolar. For surface, unit cells containing various combinations As2 dimers, missing were considered. likely structure three dimers per cell. Two such structures, nearly degenerate in energy, possible. calculated electronic structures agree with photoemission data to within ±0.3 eV. c(2×8) closely related both expected occur at surface.