Field-effect transistors based on single-wall carbon nanotubes bundles

The electric transport properties of single-walled carbon nanotubes (SWNT) bundles array have been measured. We report the fabrications and performances of nanoscale field-effect transistors (FET) based on SWNT bundles array. In addition to p-type FET, we present a new technique by which ambipolar FETs can be fabricated. The I_on/ I_off ratio of ambipolar FETs approaches 5 orders of magnitude. The reasons for ambipolar character are also qualitatively discussed. Both p-type and ambipolar FETs exhibit hysteresis in their electrical characteristics.