Effect of vacuum level on field emission from nanographite films

The effect of vacuum level on field emission from nanographite films obtained by plasma-chemical deposition is studied. The stable emission of electrons from the nanographite is observed at a threshold field of 1–2 V/μm, a current density of 0.1 mA/cm2, and a residual gas pressure in the measuring chamber of less than 10−5 Torr. At a higher pressure, the emission properties of the films gradually degrade with time. Repeat evacuation of the chamber to 10−5 Torr restores the emission properties. Such behavior of the nanographite emitters is explained by adsorption/desorption processes (reversible degradation of the emission) and the destruction of the film under the action of residual gas ion bombardment (irreversible changes).