Surface ordering of the molecular beam epitaxially grown GaAs(001)-2×4-As reconstruction

Our scanning tunneling microscopy (STM) and reflection high-energy electron diffraction (RHEED) showed that the intensity of the two-fourths fractional order feature in the RHEED pattern for the GaAs(001)-2×4 structure reflects the degree of ordering of the vacancy rows. The STM images show a high degree of surface ordering only when the RHEED produces nearly the equal intensity sharp streaks for all the fourfold fractional order diffraction. Two possible mechanisms are suggested to explain the observed STM-RHEED correlation.