Crystalline effects in elastic peak electron spectroscopy

Abstract

Elastic peak electron spectroscopy (EPES) is confined to incoherent elastic scattering, appearing in the elastic peak intensity Ie. Ion bombardment cleaning disorganizes the surface layer and might produce a component enrichment. EPES was used for the experimental determination of the inelastic mean free path of electrons on ion bombarded Si, GaAs, InP, InSb and GaSb crystals. Imperfect amorphization can produce diffraction or directional elastic peak electron spectroscopy (DEPES) effects influencing the elastic peak intensity. They appear in the Renninger plots of Ie rotating the sample around its azimuthal axis. The problem was met with the inelastic mean free path studies on InSb and GaSb crystalline samples working with a hemispherical analyser. The surface composition after Ar bombardment was checked by in situ X-ray photoelectron spectroscopy and electron energy loss spectroscopy. Using 2keV Ar+ sputtering, the enrichment of In or Ga was avoided, whereas In metallic phase was formed by 10keV ions. The energy values of diffraction on Si(111), and III–V (100) crystals was calculated for a cylindrical mirror analyser and for a hemispherical analyser. Incoherent elastic scattering occurs in the minima of Renninger plots. The goal is to avoid diffraction and DEPES effects. They are eliminated by Ar+ ion bombardment. The thickness of the amorphized layer was controlled by the Ar+ ion energy and dose.