Field-emission from long SnO2 nanobelt arrays

We report on field emission from SnO2 nanobelt arrays with the length of about 90 μm grown on silicon substrates. The turn-on field of the nanobelt arrays at the current density of 1μA∕cm2, is 4.5, 3.0, 2.4, and 2.3V∕μm as the distance between anode and cathode (d) is 0.1, 0.2, 0.35, and 0.5 mm, respectively. The current density rapidly reaches 2.1mA∕cm2 at the electrical field of 4.4V∕μm at d=0.35mm. The current density is higher than or comparable to those of the carbon nanotubes and other one-dimensional nanostructured materials. We also discuss the mechanism of high current densities and estimate the enhancement factor according to both the Fowler–Nordheim law and the reported model on micrometer-long of carbon nanotubes.