Relation between conduction property and work function of contact metal in carbon nanotube field-effect transistors.
We have investigated the relation between the conduction property and the work function of the contact metal in carbon nanotube field-effect transistors (NTFETs). The conduction type and the drain current are dependent on the work function. In contrast to NTFETs with Ti and Pd contact electrodes, which showed p-type conduction behaviour, devices with Mg contact electrodes showed ambipolar characteristics and most of the devices with Ca contact electrodes showed n-type conduction behaviour. This indicates that the barrier height of the metal/nanotube contact is dependent on the work function of the contact metal, which suggests that the Fermi-level pinning is weak at the interface, in contrast to conventional semiconductors such as Si and GaAs. We have also demonstrated nonlinear rectification current-voltage characteristics in a nanotube quasi-pn diode with no impurity doping, in which different contact metals with different work functions are used for the anode and the cathode.
Nosho
Y
Y
Department of Quantum Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan.
Ohno
Y
Y
Kishimoto
S
S
Mizutani
T
T