Coulomb blockade modulated current-voltage characteristic of a diamond field emitter

We report on an observation of a Coulomb blockade (CB) of the field emission (FE) from a single crystal diamond needle (DN) at room temperature. Two DNs were investigated showing strongly different FE characteristics. Sample 1 had a current-voltage behavior that is typical for highly resistive field emitters. In contrast, sample 2 revealed a pronounced Coulomb staircase in the current-voltage curve observed in the full current range up to 7.7 μA. By means of transmission electron microscopy a protrusion of diamond-like carbon (DLC) at the very tip of the DN could be identified as possible emitter forming the CB. The analysis is supported by electron spectroscopy as well as Raman and electron energy loss spectroscopy before and after the measurements, which help to explain the conduction mechanism and the DLC formation.