First principles calculation of field emission from carbon nanotubes with nitrogen and boron doping

We investigate the field emission properties of nitrogenated and boronated carbon nanotubes using time-dependent density functional theory, where the wave function propagation is performed using the Crank–Nicholson algorithm. We extract the current–voltage characteristics of the emitted electrons from nanotubes with different doping configurations. We found that boron doping alone either impedes, or slightly enhances, field emission. Nitrogen generally enhances the emission current, and the current is sensitive to the location of the nitrogen dopant in the nanotube. Doping with both nitrogen and boron will generally enhance emission, and the closer the nitrogen dopant is to the tip, the higher is the emitted current. The emitted charge cloud from nitrogen-doped carbon nanotubes, however, diffuse more than that from pristine ones, our simulations show the emergence of a branching structure from the charge cloud, which suggests that nitrogenated carbon nanotubes are less convenient for use in precision beam applications.

We evaluate of the impact of adding nitrogen and boron to nanotubes on field emission properties. Nitrogen enhances field emission, while boron either impedes or does not affect field emission.Figure optionsDownload as PowerPoint slideHighlights
► TDDFT for the simulation of the field emission process from nanostructures.
► Results are close to published work using similar and other methods.
► Visualization of the evolution of the charge cloud.
► Boron doping either impedes, or slightly enhances, field emission.
► Nitrogen strongly increases emission current.