The transfer of an electron from a carbon nanotube (CNT) tip into vacuum under a high electric field is considered beyond the usual one-dimensional semi-classical approach. A model of the potential energy outside the CNT cap is proposed in order to show the importance of the intrinsic CNT parameters such as radius, length and vacuum barrier height. This model also takes into account set-up parameters such as the shape of the anode and the anode-to-cathode

Sequential two-step electron tunneling from nanoparticles has been studied from a transport point of view. A steady-state balance equation for the partial electron currents is derived and solved to obtain the stationary level occupancy, which leads to the overall tunneling current as a function of the applied field. Our model explains the steplike features observed in high field tunneling experiments involving composite cathodes that incorporate