CHARACTERIZATION OF SURFACE-MORPHOLOGY IN EPITAXIAL-GROWTH

Simulated kinematic antiphase RHEED and HRLEED profiles are calculated along with the surface structure factor for a model of Fe/Fe(100) dep osition in order to clarify the interpretation of diffraction profiles in recent experiments on Fe/Fe(100) growth. Similar calculations are also presented for a self-affine surface. While self-affine surfaces d o not exhibit a characteristic RHEED peak, in the case of surfaces wit h a typical length scale the simulated RHEED profile exhibits a peak c orresponding to the typical feature size, in agreement with recent exp eriments. The existence of this peak appears to be due to the large am ount of shadowing present in low-angle RHEED, which limits the amount of destructive interference between layers. In contrast, simulated ant iphase HRLEED patterns appear to approach an invariant profile for bot h self-affine and mound-like surface morphologies. For the case of sma ll mounds, our results predict a HRLEED profile with a weak peak corre sponding to the average terrace size which moves outward with increasi ng coverage, and eventually reaches an invariant form due to angle sel ection. The disappearance of the HRLEED peak for surfaces which have l arge mound structures is explained in terms of the antiphase condition and the range of variation of terrace sizes and provides an alternati ve explanation for the HRLEED results observed in Ref. [10].