Evidence for single-electron tunneling in electron energy spectra of diamond tip field emitter

Field emission from microscale diamond tips was studied using electron energy spectroscopy. A processing at high emission currents was applied to modify the atomic surface structure of pristine diamond tips. Subsequently, staircase-like current-voltage characteristics were obtained which are typical for the single-electron tunneling occurring due to the Coulomb blockade effect in emitting carbon nanostructures formed on the surface of the diamond tips. Characteristic electron energy spectra consisted of several peaks, each corresponding to a certain charging state of the emitting nanostructure. The measured spectra were used to determine the parameters of the Coulomb blockade (e.g. charging energy) and reveal peculiar features of single-electron effects in field emission systems.