Dissociative electron attachment in H− electron stimulated desorption from hydrogenated diamond surfaces

Abstract

H− desorption cross-section and kinetic energy distribution (KED) from hydrogenated diamond surfaces stimulated by electron irradiation in the 5–45 eV range is investigated. It is determined that the desorption cross-section displays two peaks at 9 and 22 eV overlapping a monotonic increase for electron energies higher than 14 eV.The KED of the emitted ions was measured for several incident electron energies. These measurements show that for incident electrons of up to ∼11 eV the most probable kinetic energy of H− ions monotonically increases from about 1.5 to 3 eV. For higher incident electron energies the ion energy distribution peaks at about 1.5 eV and is nearly constant. Ion desorption at specific energy as function of incident electron energy is also measured. These results suggest two different mechanisms for the desorption process: the mechanism of H− electron stimulated desorption from hydrogenated diamond surface displaying peaks at 9 and 22 eV is driven by dissociative electron attachment, the other mechanism involves dipolar dissociation processes with a threshold at ∼14 eV.