Discharging, enhancement, and control of electron emission of hydrogen free diamond film surfaces by subband gap light illumination

We report on the surface charge elimination, enhancement, and control of secondary electron emission from hydrogen free polycrystalline diamond film surfaces subjected to continuous low energy electron irradiation. Hydrogen free diamond surfaces severely charge under electron irradiation by nonresonance charge trapping in surface π bonds associated with surface reconstruction. Concurrent electron irradiation and illumination of the diamond surface with subband gap photons enhance the secondary electron emission yield and discharge the surface accumulated charge. These effects are suggested to be associated to direct photoexcitation of trapped charge in midgap surface states which result in neutralization and unpinning of the surface bands