A NEW FORMALISM FOR ANGLE-RESOLVED X-RAY PHOTOELECTRON-SPECTROSCOPY (ARXPS) AND AUGER-ELECTRON SPECTROSCOPY (ARAES) OF NONCRYSTALLINE SOLIDS TAKING ELASTIC ELECTRON-SCATTERING INTO ACCOUNT

The effects of elastic electron scattering in non-crystalline solids on the angle-resolved mode of the electron spectroscopic techniques have been studied with a Monte Carlo model. The results of this study demonstrate that elastic scattering must be accounted for in the formalism of angle-resolved Auger electron spectroscopy and angle-resolved x-ray photoelectron spectroscopy. The use of a recently introduced attenuation law for signal electrons in the angle-resolved electron spectroscopies is studied. The effects of elastic scattering are incorporated in this attenuation law by the use of one additional parameter that depends on the energy and the material. This parameter, the so-called attenuation parameter, can be found in the literature.1 It was found that this new attenuation law yields an accurate description of the influence of elastic scattering on the angular distribution of signal electrons, which is by far superior to the straight-line approximation. Neglecting the influence of elastic scattering introduces- an error of approximately 50% in the calculated overlayer thicknesses. The conventional algorithms to restore depth profiles from angle-resolved experiments can be modified easily to account for elastic scattering through the use of the new attenuation law. This yields restored thicknesses which agree within 1% with the model thicknesses. Another important finding of this study for the angle-resolved electron spectroscopies is that elastic scattering poses a strict upper limit to the depth range that can be analysed by means of angle-resolved measurements.