DETECTING STACKING-FAULTS DURING EPITAXIAL-GROWTH BY LOW-ENERGY-ELECTRON DIFFRACTION

We study the sensitivity of LEED to stacking faults in the early stage s of epitaxial growth. By theoretical simulation of stacking faults in different locations, in particular for Cu/Cu(111), Co/Cu(111), and p( 4 x 4)Pb/Cu/Cu(111), we show that quantitative LEED can detect stackin g faults down to three or four layers deep into the substrate. This is also true in the presence of a surfactant layer. The modification of the intensity spectra by stacking faults is large enough to be identif ied by visual comparison with defect-free surfaces. In the cases where different stacking sequences coexist on the surface, a minimum covera ge of 30%-50% imperfect stacking sequences is needed in order to be cl early detected in the LEED I-V curves. Therefore, our results provide guidance to conduct experiments where early detection of stacking faul ts is important.