COMPARISON OF REFLECTION HIGH-ENERGY ELECTRON-DIFFRACTION AND LOW-ENERGY-ELECTRON DIFFRACTION USING HIGH-RESOLUTION INSTRUMENTATION

Reflection high-energy electron diffraction (RHEED) is a standard diff raction method in surface science, but contrary to low-energy electron diffraction (LEED) the analysis of morphology and defect structure is not as reliable due to inelastic scattering and a more complicated sc attering geometry. These difficulties are mastered by adequate instrum entation and measuring procedures as done with a novel high-resolution , energy-filtered RHEED instrument. The elastically scattered intensit y close to the specular beam is measured for many angles of incidence in both directions - parallel and perpendicular to the shadow edge. Th e series of profiles obtained perpendicular to the shadow edge have be en used to produce profiles with constant momentum transfer perpendicu lar to the surface corresponding to LEED profiles with ultra-high reso lution. By means of. these profiles, the surface morphology is charact erized on the basis of kinematic approximation as done in LEED with mu ch success. The validity of that procedure is demonstrated for homoepi taxy on Si(111) by comparison of the results with LEED and STM data. ( C) 1997 Elsevier Science B.V.