Electron inelastic mean free path (IMFP) in single crystal BeO by Rutherford backscattering (RBS) and Auger electron spectroscopy (AES)

Quantitative studies of oxidation kinetics by electron spectroscopies require knowledge of the IMFP of electrons in the oxide. In general, IMFP data for oxides are not available. A method is presented for the determination of the IMFP in beryllium oxide using RBS to determine the oxide thickness and AES to measure the chemically shifted Be Auger electron intensity from the BeO-covered surface and the unshifted signal from the Be substrate. Using the normal exponential attenuation relationship between material thickness and the AES signal passing through the material, an IMFP of 6.0 ±0.8 monolayers is determined for ~ 100 eV electrons in BeO. In these experiments the oxide was grown at a temperature (~ 700 K) which ensured a good single crystal epitaxy on the substrate. Because of this good structural characterization, the IMFP can be presented equally well in units of monolayers or in units of length. The accuracy of the method and its general applicability to other materials is discussed.