Ballistic Transport in Semiconducting Carbon

Abstract. We report on electronic transport in devices consisting of individual semiconducting singled-walled carbon nanotubes (SWNTs) grown by a chemical vapor deposition technique and contacted by metal electrodes. Lx)w-temperature electronic transport at negative gate bias indicates the SWNTs act as single quantum dots with a length on order of the electrode spacing, indicating that the mean free path is greater than the contact spacing (~ljmi). Upon increasing gate bias, an intermediate multiple quantum dot regime is observed, followed by a gapped region at positive gate bias. At room temperature and zero gate bias a mean free path of 700nm is determined using electrostatic force microscopy to probe the local potential in the SWNT. Ballistic electronic conduction has been observed in metallic single-walled carbon nanotubes (SWNTs) [1], but the electronic transport in semiconducting SWNTs has been reported as consistent with tunneling through a series of closely spaced (~100nm) low transmission conduction barriers [2]. The SWNTs in the above studies were prepared using a laser vaporization technique, with subsequent treatment in an ultrasonic bath in order to separate individual SWNTs from bundles. Here we report measurements on individual semiconducting SWNTs prepared directly on insulatin