Surface structures of the GaAs(0 0 1)2×4 studied by RHEED rocking curves

RHEED rocking curves have been measured at α, β and γ phases of the 2×4 structures of GaAs(0 0 1) surfaces during homoepitaxial growth. The rocking curves at the β phase are very similar to the curves obtained by the literature Surf. Sci. 169 (1986) 176. We conclude that the 2×4 structure at the β phase is that of the 2-dimers–2-missing-dimers model. For the α and γ phases, the peak positions of the rocking curves are nearly the same as the peak positions of the curves at the β phase. For the (0 0), (0 1/4) and (0 1) rods, rocking curves for the three phases are very similar. Therefore it is concluded that the three phases of the 2×4 structure are basically the same structure with different defect distributions. We propose a determination method of surface structure models using intensities of rocking curves which are integrated through certain glancing angles.