Fabrication of n-type carbon nanotube field-effect transistors by Al doping

Abstract

We report the effect of an Al layer, covering the central part of the nanotube channel, on the electrical transport properties of carbon nanotube field-effect transistors (CNFETs). The CNFETs, consisting of single-walled carbon nanotube or double-walled carbon nanotube between two Pd electrodes on top of SiO2 layer, which showed p-type or ambipolar transport behaviors, exhibit clear n-type characteristics after the Al deposition. We ascribe such conversions into n-type behaviors to the electron doping in the Al-covered nanotube region, which results in the bending of the nanotube bands nearby the edges of the Al layer. This technique, Al deposition under a high vacuum, may give rise to a practical fabrication method for the n-type CNFET, which may enable us to develop complementary logic nanotube electronic devices.