Study of field emission characteristics of carbon with the scanning atom probe

After obtaining the Fowler-Nordheim plot (F-N plot) of various carbon specimens including artificial diamonds and carbon nanotubes (CNTs), the Surface composition of the specimens is analyzed by the scanning atom probe (SAP). Since the emitters vary from a sharp and slender CNT to a dull corner of a small diamond grain, the slope of the F-N plot is hardly related to the work function. Accordingly, the slope and intercept of the F-N plot are plotted on a Sasaki-Kaneko (S-K) chart. Even when the slopes of the F-N plots vary in a wide range, the points corresponding to the slopes and intercepts of the F-N plots are aligned on the S-K chart as suggested by the analytical calculation of the field strength directly above the emitter surface. Our results indicate that the work function of CNTs is smaller than that of the other carbon specimens and increases with the removal of the absorbed hydrogen.