ELECTRON-CAPTURE AND LOSS IN THE SCATTERING OF HYDROGEN AND OXYGEN IONS ON A SI SURFACE

We present the results of a study of H- and O- formation in collisions between 0.5-4 keV hydrogen ions and oxygen ions and atoms with an Si surface. Measurements of scattered negative ion fractions are reported . These are found to be of the same magnitude as for clean metal surfa ces like Al. A dynamic velocity-dependent effect in electron capture i s observed. A non-resonant, velocity-dependent, charge transfer proces s, involving localized dangling bond surface states, is invoked io exp lain this observation. The production of positive ions is discussed. ( C) 1998 Published by Elsevier Science B.V.