Stabilization of field electron emission from carbon nanofibers using ballast resistance

Abstract

Stabilization of field emission (FE) from carbon nanofibers grown on a metal tip has been extensively studied using ballast resistances of 1 ≤ R ≤ 1500 MΩ at electron currents of 1≲I≲100μA. The FE current stability ɛ(R) = ΔI(R)/Im strongly depends on the mean current Im, while the data points of the relative stability Γ(R) = ɛ(R)/ɛ(0) plotted as a function of R multiplied by Im could be crudely reduced into a curve. In the stabilization studied here, extracting voltage fluctuation ΔV(R) was weakly induced by the current fluctuation ΔI(R). The current stability ɛ(R) and the voltage fluctuation ΔV(R) could be interpreted by employing a dynamical impedance of z = (dI/dV)−1 evaluated from the experimental I–V curve. The optimum current stability of ɛ(R) ∼ 0.002 was achieved using the resistance of R ∼ 10 MΩ around the highest FE current of Im = 80 μA, while the extracting voltage stability was η(R) = ΔV(R)/V ∼ 0.001 [ΔV(R) ∼ 2 V] at R ∼ 10 MΩ and Im ∼ 80 μA.