Electron-Stimulated Modification of Si Surfaces

Abstract

Scanning tunneling microscopy studies show significant structural modifications that involved atom desorption and displacement following mild irradiation by electrons of 90--2000 eV. For $\mathrm{Si}(111)\ensuremath{-}(7\ifmmode\times\else\texttimes\fi{}7)$, adatom layer vacancies increased monotonically with incident energy. For $\mathrm{Si}(100)\ensuremath{-}(2\ifmmode\times\else\texttimes\fi{}1)$, irradiation produced dimer vacancies, and ad-dimers as Si atoms transferred to the terrace. The modification processes are tied to the energy distribution of electron-hole and electron attachment states achieved by inelastic cascade scattering. Hence, beams previously believed to be benign induce surface structural modifications.