First-principles study of quantum tunneling from nanostructures: Current in a single-walled carbon nanotube electron source

We present a first-principles calculation of the emission current in a single-walled carbon nanotube electron source. We have employed the nonequilibrium Green's function and Fisher-Lee's transmission formulation to describe electronic transport through the system. The simulation results reproduce the trends observed in experimental data closely and, in particular, the current saturation and deviation from the Fowler-Nordheim behavior. The proposed numerical approach is useful whenever a region of vacuum is present in the system Hamiltonian.