Surface versus Sub-Surface D? Electron Stimulated Desorption from Diamond Surfaces

Abstract

In this work we report on a study of the low energy electron stimulated desorption (ESD) of D— from in-situ hot filament deuterated surfaces of diamond films. For incident electron energies in the 5–15 eV range a dissociative electron attachment (DEA) processes occur. The cross section for D— ESD obtains a maximum value at ∼9 eV. Ion kinetic energy distribution (KED) measurements show, that in the DEA regime desorption results in a narrow peak, whose energy position increases with incident electron energy at an energy which corresponds – minus a multiphonon excitation factor – to the thermodynamic limit in agreement with gas phase considerations. To study the effect of inelastic interactions between the desorbing D— ions and the surface KED measurements were performed as function of desorbing angle with respect to the surface normal. It was found that with increasing angle from the surface normal the D— KED broadens and its lower energy component increases in intensity. These results clearly show that inelastic interactions between the outgoing D— and the solid surface take place. Our results show that ESD may be used to determine the presence of surface versus sub-surface hydrogen (deuterium) adsorbed on diamond.