The atomic geometry of GaAs(110) revisited

Improvements in surface structure determination methodologies based on the analysis of experimental low-energy electron diffraction intensities are utilized to perform an R-factor structure determination for GaAs(110). In addition to the commonly-accepted structure (a top-layer bond-length-conserving rotation of the As outward and the Ga inward characterized by ω₁ = 27°, relaxation of the top layer toward the bulk by 0.05 Å, and a relaxation of the second-layer Ga outward and As inward by 0.06 Å), a new structure is found which consists of a top-layer bond-length-conserving rotation of ω₁ = 7°, relaxation of the top layer away from the bulk by 0.05 Å, and a converse second-layer relaxation of the Ga and As by 0.03 Å. This new structure may be distinguished from the accepted one and refinements thereof by examining the integrated intensities of the diffracted beams. When these are considered, a refinement of the accepted structure still provides the best description of measured low-energy electron diffraction intensity data, and is manifestly compatible with other recent analyses of photoemission and isochromat data.