Determination of absolute thickness and mean free path of thin foil specimen by zeta-factor method

The zeta-factor method is applied to the thickness determination of thin amorphous specimens where the convergent-beam electron diffraction method is not applicable. Characteristic X-ray intensities are first measured using standard specimens in order to determine zeta-factors. These zeta-factors are then used to determine local thicknesses of an amorphous Si and an amorphous Al alloy. Electron energy-loss spectroscopy (EELS) spectra are acquired at the same positions as for the X-ray measurements. Thus, using the thicknesses measured from the zeta-factor method, the electron mean-free path is determined through the EELS log-ratio method. The mean free path is measured as a function of the collection semi-angle, beta, and specimen thickness, and it is also compared with theoretical values. Furthermore, the mean free path of amorphous Si is compared with that of the crystalline Si.