Ab initiostudy of Schottky barriers at metal-nanotube contacts

The type of barrier at a metal/CNT junction is one of the key issues in nanotube electronics. Despite the extensive experimental work done to clarify this issue, there is no consensus in the nano-electronics community. We present here the first ab initio calculation on the Schottky barrier and tunneling barrier height of an idealized metal (Au, Pd, Pt) semiconducting (8,0) nanotube junction. All three metal species form Schottky barriers when contacting small diameter nanotubes. Two most important atomic geometrical factors influencing the Schottky barrier height are identified as the metal species and its surface orientation. Pd is found to have the lowest Schottky barrier. Our simulation results give useful insight into the on going experiments.