DIFFERENTIAL ELASTIC-SCATTERING AND BACKSCATTERING CROSS-SECTIONS OF H, SI AND O IN THE LOW-ENERGY (2-50 EV) RANGE FOR ELECTRON-SPECTROSCOPY ON POROUS SI

Hydrogen is found to influence the porous Si/PSi system. H atoms canno t be defected by AES or XPS, but profound effects have been observed o n PSi using the elastic peak electron spectroscopy (EPES) in the 50-10 0 eV range after HF treatment of PSi samples. Limited numbers of low e nergy cross sections are available in the literature. The data of Joy et al are confined to 20 and 50 eV. The differential cross sections of electrons have been calculated in the present work in the 2-50 eV ran ge for H, Si and O, i.e. elements composing the surface of PSi. The re lativistic and nonrelativistic PWEM method was used in calculations. T he electron-atom interaction was described by the TFD potential, using a recent approximation, in view of considerable errors of earlier app roximations. Some experimental data are available for gaseous hydrogen . They turn out to be in good agreement with our calculated values. Th e total elastic, scattering, the total backscattering and the backscat tering cross sections integrated within the angular range (124-176 deg rees) of RFA, sigma(RFA), have been calculated for monolayer of H, Si and O. They strongly increase with decreasing energy. In the case of S i, a broad maximum is observed and strong decrease below 20 eV, with a deep minimum between 2 and 10 eV. Here sigma(RFA,H) >> sigma(RFA,Si) EPES is promising in this very low energy range for the system H/Si, a nalogous to H/W.