Noise spectroscopy of transport properties in carbon nanotube field-effect transistors

Transport properties of single-walled carbon nanotube (CNT) structures with Pd contacts were studied using noise spectroscopy. The high values of the mobility and low noise level are characteristic of high-quality CNT material. The detailed analysis of the transport and noise properties of the CNT structure with back gate topography allows us to study the transport determined by Schottky barriers and by pure CNT channel conductivity and to establish their separate contribution to the total conductivity of the structure. It was demonstrated that at small gate overdrive the main source of flicker noise is related to the Schottky barriers of the CNT–FETs. With increasing gate voltage, the magnitude of flicker noise decreases and at a certain gate voltage it is only determined by the transport properties of carbon nanotubes with a noise level lower by one order of magnitude. In contrast to previous studies where flicker noise determined the excess noise of CNT-based structures, we registered generation–recombination noise components in our structures and studied their behavior in a wide temperature range. This allowed us to investigate the origin of traps capturing the carriers, which considerably affects the noise and transport properties of CNT structures.