Electrical Heating and Coulomb Gap in SWNT/ PMMA Composites

Abstract

In this paper, we investigate the transport properties of single wall nanotubes (SWNT) /polymethylmetacrylate (PMMA) thin films. We show that transport on the composite films close to the percolation threshold yields information about the nanoscopic properties. Transport occurs through 3D hopping of localized carriers in presence of a soft Coulomb gap. This gap likely originates from the charging energy of the isolated tubes. Its magnitude decreases by increasing the nanotubes content because of the partial screening due to neighbouring tubes. Large non linearities are also observed in the current‐voltage characteristics. They come from electric heating of the conduction gas of metallic tubes, the transport mechanism being preserved. The electrical temperature concept allows us to describe all these transport properties within a unique comprehensive model.