On the structure of reconstructed Si(001)2×1 and Ge(001)2×1 surfaces

Abstract
Full dynamical LEED intensity calculations have been carried out on Si(001) and Ge(001) surfaces distorted from bulk in the first three layers as in the surface-dimer model proposed previously. Comparison with experimental data indicates that for Si(001), the model produces the best agreement achieved so far, but the overall agreement is not good enough to qualify as satisfactory. For Ge(001) there is practically no agreement with experiment. Variations of the dimer model are suggested which introduce distortions with 2*2 and c(4*2) periodicities and explain qualitatively a number of experimental observations, although no quantitative model has been found that reproduces satisfactorily the experimental LEED intensity data available.