Electrical properties of carbon nanotube FETs

Abstract

The electrical properties of carbon nanotube FETs (CNTFETs) have been studied in detail. The conduction type of the CNTFETs was dependent on the work function of the contact metal, which suggests that Fermi level pinning at the metal/nanotube interface does not happen. Based on the two-probe and four-probe resistance measurements, it was shown that the carrier transport at the contact is explained by the edge contact model even in the diffusive regime. The chemical doping using F4TCNQ was effective to reduce not only the channel resistance but also the contact resistance. It has also been shown that the surface potential measurement based on the electrostatic force detection in the scanning probe microscopy was effective in studying the behavior of the CNTFETs such as the transient behavior and the effect of the defects. Finally, in the CNTFETs fabricated using plasma-enhanced (PE) CVD-grown nanotubes, most of the drain current could be modulated by the gate voltage with little non-depletable drain current suggesting the preferential growth of the nanotubes with semiconducting behavior.