Low energy electron trapping in hydrogenated diamond surfaces by resonance electron attachment

We investigate secondary electron emission (SEE) of hydrogenated diamond films subjected to incident electron irradiation at energies between 5 and 20 eV. For the hydrogenated films it was found that the SEE intensity decays under continuous electron irradiation. This effect is explained as due to electron trapping by resonance electron attachment into C-H (ads) bonds in the near-surface region of the hydrogenated diamond films resulting in the formation of a depletion layer and upward surface band bending. The SEE intensity decay rate from the hydrogenated diamond surface was measured as a function of incident electron energy and compared to the H− desorption cross section by dissociative electron attachment. Both were found to display a peak at ∼9 eV. The similar dependence of these two phenomena with incident electron energy suggests that the main mechanism of electron trapping is by resonant electron attachment of incident electrons onto C-H bonds present within the near-surface region of the hydrogenated diamond films. Increasing the surface temperature results in an enhanced electron emission and less efficient surface charging.