ELECTRON-STIMULATED DESORPTION FROM HYDROGEN AND ALKALI ADSORBED SI(111) SURFACE

Electron stimulated desorption from hydrogen and alkali adsorbed Si(111) surface is studied by Time-of-Flight mass spectroscopy. For hydrogen adsorption H+ desorption induced by the Si-LVV Auger transition is first observed above 100 eV of the electron energy. In the threshold region, the desorption is explained by the localization of two holes in the bonding orbital between hyrdrogen and silicon produced by the shake-up excitation reported in the literature. For alkali adsorption, only H+ desorption is observed whereas desorption of alkalis is quite rare. The kinetic energy distribution of H+ ions consists of three components. Each component shows a different dependence on the incident electron energy. © 1990 Pergamon Press plc.