Electron beam effects on diethylsilane-covered Si(100) surfaces investigated by electron stimulated and temperature programmed desorption

摘要

The effect of low-energy electron irradiation on adsorbed layers of diethylsilane (DES) on the Si(100) surface at 100 K were studied using temperature programmed desorption (TPD) and electron stimulated desorption (ESD). As has been observed previously, TPD studies of adsorbed DES have shown desorption of both molecular hydrogen and ethylene. Adsorption of DES at 100 K also results in a loosely bound layer that desorbs molecularly at a temperature of similar to140 K. Strong evidence exists for thermal removal of ethylene from the surface during programmed heating via a beta-hydride elimination process. Irradiation of the dosed surface with electrons results in a number of interesting effects. Electron-induced enhancement of both hydrogen and ethylene desorption from Si(100) is observed. In addition, both neutral and ionic desorption of surface species was observed, induced by electron irradiation. Desorption of neutral species having masses of 2, 15 and 28 indicate electron-induced removal of hydrogen and ethylene, with a methyl group appearing as a result of ethylene dissociation. Hydrogen removal occurs from two distinct states, as identified by the decay of neutral hydrogen from the surface, characterized by two decay constants. Analysis of the energy of desorbing H+ species suggests two distinct kinetic energy distributions at 1.8 and 4.1 eV, which contribute to the desorption signal. Copyright (C) 2003 John Wiley Sons, Ltd. [References: 13]