Surface photo-voltage effect of hydrogenated diamond subjected to low energy electron irradiation

In this paper we report on the influence of sub-band gap photon illumination on the electron emission of hydrogenated diamond surfaces subjected to continuous low energy electron irradiation. Hydrogenated diamond surface traps charge by resonance electron attachment (REA) and formation of C–H(ads)− anionic transient surface species with a maximum cross section at an incident electron energy of ∼ 9 eV. The steady state population of these anionic surface species results in up-wards surface band bending and consequent decrease of low energy electron emission. It is demonstrated that concurrent low energy electron bombardment and illumination of the diamond surface with sub-band gap photons enhances the secondary electron emission yield of diamond. It is argued that these effects are associated to a surface photo-voltage effect, which results in unpinning of the surface band.