The electron field emission properties of individual multiwalled carbon nanotubes have been examined using a combined STM-TEM microscope. The measured electron emission, for low emission currents, can be fitted with a standard Fowler-Nordheim model. For higher electron emission, above 10μA for an individual carbon nanotube, we observe a significantly increased emission current leading to a nonlinear Fowler-Nordheim plot. The nonlinearity is caused by thermally enhanced electron emission due to Ohmic heating of the carbon nanotube. This is verified by modeling the electron field emission current. In addition to the influence of radiative cooling and the temperature dependence of the nanotube resistivity, we clearly show that a consideration of the temperature change due to the electron emission process itself, known as the Nottingham effect, is crucial to obtain good agreement with the experimental data.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - 15 Aug 2005|