Nonlinear characteristics of the Fowler–Nordheim plots of carbon nanotube field emission

Abstract

The barrier between substrate and field emitters can dominate the overall process of field emission. Carbon nanotube (CNT) films were synthesized by thermal chemical vapor deposition (CVD) on silicon substrate covered with a very thin SiO2 layer as the interface contact barrier. The current versus applied voltage curve shows a high turn-on voltage, and the Fowler–Nordheim (FN) plot exhibits nonlinearity characteristics and departures from the original line and exhibits current saturation in the high-voltage region. However, the FN plot of CNTs grown on Si substrates without SiO2 layers had no obvious critical voltage and approximately followed the FN law in our experimental voltage region. The reasons for the nonlinearity of FN plots of CNTs grown on a SiO2 layer were discussed in terms of circuit theory.