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    Applied Surface Analysis Monday Sessions
       Session AS-MoA

Paper AS-MoA4
Surface Excitations of Medium Energy Electrons in Metals and Semiconductors

Monday, October 29, 2001, 3:00 pm, Room 134

Session: Quantitative Analysis and Data Interpretation II: Electron Spectroscopies
Presenter: W.S.M. Werner, Vienna University of Technology, Austria
Authors: W.S.M. Werner, Vienna University of Technology, Austria
W. Smekal, Vienna University of Technology, Austria
C. Tomastik, Vienna University of Technology, Austria
H. Stoeri, Vienna University of Technology, Austria
Correspondent: Click to Email
Reflection energy electron loss spectra (REELS) have been measured for several metals and semiconductors (Be, Al, Si, V, Fe, Co, Ni, Cu, Ge, Mo, Pd, Te, Ta, W, Au, Pb) in the medium energy range (150-3400 eV) for normal incidence and an emission direction of 60 with respect to the surface normal. The ratio of the number of electrons that induced a surface excitation to the intensity of the elastic peak was extracted from each spectrum providing the total surface excitation probability (SEP). For the nearly free electron materials the results agree reasonably with free electron theory while significant deviations are observed for the other materials. In all cases the SEP is proportional to the time the probing electron spends in the vicinity of the surface. It is generally found that the surface excitation probability decreases with the generalized plasmon energy. A simple predictive formula to estimate the surface excitation probability for medium energy electrons entering or leaving an arbitrary material is proposed.