Highly-spatial resolved surface structure and composition by LEEM image intensity analysis

Controlling the local structure and composition of a surface alloy is of great importance in thin film technologies. ~However, measuring the alloy's heterogeneity is very difficult, because existing experimental techniques either assume lateral homogeneity or have limited subsurface or chemical sensitivity. ~In this work~we have analyzed the electron diffraction intensity vs. incident energy curves of the (00) beam acquired from low-energy electron microscopy (LEEM) images. ~In contrast to conventional LEED-IV we are able to extract structural and local composition in the surface region with a lateral resolution of 8 nm. Two challenges in applying multiple electron scattering calculations to the analysis of LEEM data are the low and limited electron energy range (10 to 100 eV), which we address by a careful choice of the energy-dependent real and imaginary part of the optical potential. Our analysis of the LEEM IV curves for the clean Cu(001) and Pd/Cu(001) surfaces gives excellent agreement between experimental and best-fit data and good agreement with previous structural investigations. Our new analysis technique is capable of determining surface structure and composition with high accuracy.