QUANTITATIVE-ANALYSES OF RHEED PATTERNS FROM MBE GROWN GAAS(001)-2X4 SURFACES - COMMENT

In a recent paper (Y. Ma, S. Lordi, P.K. Larsen and J.A. Eades, Surf Sci. 289 (1993) 47) a multislice formalism combined with an edge-patching method was used in the quantitative analysis of RHEED patterns from the As-rich GaAs(001)-2 x 4 surface. We correct certain of the statements made in this paper concerning the unreliability of previously reported RHEED calculations and RHEED surface structure analyses. We then discuss details of the multislice calculations of Ma et al. and the pattern fitting procedure used. With reference to our own RHEED calculations for this surface, using a 2D Bloch wave formulation, we conclude that there are problems in the pattern fitting procedure and that this method can by no means be considered as reliable as reported in earlier RHEED analyses.