Transport characteristic control of field-effect transistors with single-walled carbon nanotube films using electrode metals with low and high work functions

We have fabrficated field-effect transistors with single-walled carbon nanotube films using various work-function metals (Mg, Al, Ti, and Ni) as the source and drain electrodes to control the transfer characteristic. The n-type transfer characteristic is obtained from the device with low-work-function metal (Mg), and the p-type characteristic is obtained from the device with medium- and high-work-function metals (Al, Ti, and Ni). The ambipolar characteristic of the device with Mg electrodes in air is converted to the n-type characteristic by maintaining in vacuum. The device with Mg as a drain electrode and Ni as a source electrode shows the ambipolar characteristic at small and large drain-source voltages. This device might be able to simultaneously inject electrons and holes into a SWNT.