STATISTICAL TREATMENT OF DYNAMICAL ELECTRON-DIFFRACTION FROM GROWING SURFACES

Statistical methods developed previously for the evaluation of the electrical conductivity of metals and the description of the propagation of waves through random media are applied to the problem of scattering of high-energy electrons from a rough growing surface of a crystal where the roughness is caused by local fluctuations of site occupation numbers occurring during the growth. We derive the relevant Dyson and Bethe-Salpeter equations and define the short-range order correlation functions that determine the behavior of the reflection high-energy electron diffraction (RHEED) intensities. To analyze the temporal evolution of these correlation functions, we employ an exactly solvable model of the local perfect layer growth [A. K. Myers-Beaghton and D. D. Vvedensky, J. Phys. A 22, L467 (1989)]. Our approach makes it possible to separate individual contributions of various processes that give rise to oscillations of the RHEED reflections. We found that provided that the Bragg conditions of incidence are satisfied, it is the diffuse scattering by the disordered surface layer which is largely responsible for oscillations of the RHEED intensities. The temporal evolution of the angular distribution of the diffusely scattered electrons exhibits the effect of enhancement of the intensity of the Kikuchi lines with increasing surface disorder, as was observed experimentally [J. Zhang et al., Appl. Phys. A 42, 317 (1987)]. An explanation of the origin of this phenomenon is given using the concept of the final-state standing wave pattern. © 1994 The American Physical Society.