Effects of Cs deposition on the field-emission properties of single-walled carbon-nanotube bundles

We report the effects of Cs deposition on the field-emission (FE) properties of single-walled carbon-nanotube bundles. We observe that Cs deposition decreases the turn-on field for FE by a factor of 2.1–2.8 and increases the FE current by six orders of magnitude. After Cs deposition, the FE current versus voltage $\mathrm{(I–V)}$ curves show non-Fowler–Nordheim behavior at large currents, consistent with tunneling from adsorbate states. At lower currents, the ratio of the slope of the FE $\mathrm{I–V}$ curves before and after Cs deposition is approximately 2.1. Exposure to ${\mathrm{N}}_2$ does not decrease the FE current, while exposure to ${\mathrm{O}}_2$ decreases the FE current.