Thickness dependent ballistic electron emission microscopy (BEEM) studies have been performed on Au/Fe81C19/Si(001) and Au/Si(001) Schottky diodes at 80 K. The Schottky height was measured to be 0.70 +/- 0.02 eV for the Fe81C19/Si(001) interface. Electron attenuation lengths were extracted from the slope of the semilog BEEM current versus the thickness of the Fe81C19 layers for electron energies ranging from 1.0 to 1.5 eV. In this range the attenuation length was found to decrease with increasing energy from 4.1 +/- 0.9 to 2.5 +/-0.6 nm, which indicates that some electron-electron scattering is occurring in the metal overlayer. This decrease is slightly greater than predicted for a free clectron gas system, resulting from the complex structure of the Fe81C19 film. (c) 2006 American Vacuum Society.