Temperature-dependent transport and1/fnoise mechanisms in single-walled carbon nanotube films

Abstract

The temperature dependence of 1 / f noise and resistivity in single-walled carbon nanotube ͑CNT͒ films are studied. We find that as the temperature decreases, resistivity monotonically increases whereas 1 / f noise amplitude first decreases, then increases, reaching a minimum at around 40 K. At temperatures considerably smaller than 40 K, the temperature dependence of both resistivity and 1 / f noise amplitude can be explained by three-dimensional Mott variable-range hopping, which is due to localization effects that result in an insulating behavior in CNT films. At higher temperatures, on the other hand, the dependence of resistivity on temperature can be explained by fluctuation-induced tunneling. In this high-temperature regime, we analyze the temperature dependence of the noise amplitude to extract the density of fluctuators as a function of their energy. Our results show a characteristic peak between 0.3 and 0.6 eV that is responsible for the majority of 1 / f noise. We also find that, due to its correlation with the number of carriers, the noise amplitude is very sensitive to CNT film device dimensions, especially near the percolation threshold where the resistivity increases. These results not only provide fundamental physical insights about transport and 1 / f noise mechanisms in CNT films at different temperatures but also help assess the suitability of these films for device applications.

Length and temperature dependent 1/f noise in vertical single-walled carbon nanotube arrays

“…Because of the large difference in the magnitude of A, the values for each device have been normalized to their measured values at 294 K. Below 250 K, 1/f noise decreases with temperature to a value 40 times less than the peak value in the shorter (100 nm and 200 nm) devices and a value 20 000 times less in the longer (320 nm and 400 nm) devices. Above 250 K, the 1/f noise tends to slightly increase as temperature rises to up to 400 K. This trend is similar to that measured by Behnam et al 6 The SWCNT arrays tested involve a combination of metallic and semiconducting nanotubes connected electrically in parallel. Reza et al 19 developed a method for separately measuring the 1/f noise contribution from semiconducting and metallic CNTs connected electrically in this manner.…”

“…When temperature decreased from room temperature, the noise prefactor dropped to a minimum near 200 K. Further reductions in temperature lead to an increased noise prefactor. A similar trend was noted by Behnam et al 6 in the temperature range from 1-300 K. The noise prefactor was found to have a maximum at about 250 K and a minimum value at 40 K in the SWCNT films.…”

1/f noise and mechanisms of the conductivity in carbon nanotube bundles

“…Noise models of hopping conductivity in semiconductors predict a quadratic dependence of the noise as a function of the current through the sample ( = 2). The experimental results confirm these findings [11][12][13][14][15]. Since our results contradict these data, we consider the origin of such a disagreement in more detail based on the analysis of experimentally obtained results.…”

Conduction properties of thin films from a water soluble carbon nanotube/hemicellulose complex

“…The inter-tube resistance is most simply described as dependent on an activation energy, and the total resistance can be thought to be the result of a network of resistors where usually the inter-tube resistance dominates [19]. However, A c c e p t e d M a n u s c r i p t many works also apply Variable Range Hopping theories that do not directly build on mechanical network connectivity [20,21].…”