Local variation of metal-semiconducting carbon nanotube contact barrier height

Carbon nanotubes provide great promise for future use as electronic devices. Previously we have used a conducting-tip atomic force microscope to measure the local field effect in a metal-semiconducting C nanotube-metal device. Here we propose a consistent electrostatic model that incorporates the image force, electric field and tip potential and describes how the latter reduces the potential barrier seen by thermionically emitted carriers in the metal-nanotube junction. The model describes a position-dependent barrier change, consistent with experimental data.