Schottky barriers and Coulomb blockade in self-assembled carbon nanotube FETs

We report low-temperature electronic transport in batch-processed single-walled carbon nanotube (SWNT) field-effect transistors (FETs). SWNTs are in situ synthesized and wired between submicrometer metallic electrodes in a single-step process involving hot-filament-assisted chemical vapor deposition. FETs show a pronounced ambipolar field effect between 1 and 300 K. Moreover, the gate dependence exhibits hysteresis at any temperature because of the extraction and trapping of charges. We find Schottky barriers at the SWNT/metal contact to be responsible for the field effect. Below 30 K, potential barriers along the SWNT induce a Coulomb blockade at low drain-source bias, leading to the suppression of the field-effect gain and inducing fluctuations in the transconductance.