Detecting stacking faults during epitaxial growth by low energy electron diffraction

We study the sensitivity of LEED to stacking faults in the early stages 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 stacking 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 identified by visual comparison with defect-free surfaces. In the cases where different stacking sequences coexist on the surface, a minimum coverage of 30%-50% imperfect stacking sequences is needed in order to be clearly detected in the LEED I-V curves. Therefore, our results provide guidance to conduct experiments where early detection of stacking faults is important.