Stimulated desorption of D− from diamond: surface versus sub-surface processes via resonance dissociative electron attachment

Abstract

In this work, we report on a study of low-energy electron stimulated desorption (ESD) of D− from in situ hot filament deuterated surfaces of diamond films. This deuteration procedure ensures that deuterium is predominantly adsorbed onto the diamond surface and no significant diffusion underneath the surface takes place. The cross-section for D− ESD through dissociative electron attachment (DEA) obtains a maximum value at ∼9 eV, whereas the dipolar dissociation process displays a threshold ∼14 eV. The ion kinetic energy distribution (KED) measurements show that in the DEA regime, desorption results in a narrow peak. To study the effect of inelastic interactions between the desorbing D− ions and the surface, in the DEA regime, KED measurements were performed as a 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. Our results show that low-energy ESD in the DEA regime may be applied to determine the presence of surface vs. sub-surface hydrogen (deuterium) in diamond.