Universal crossover of the charge carrier fluctuation mechanism in different polymer/carbon nanotubes composites

Abstract

Carbon nanotubes added to polymer and epoxy matrices are compounds of interest for applications in electronics and aerospace. The realization of high-performance devices based on these materials can profit from the investigation of their electric noise properties, as this gives a more detailed insight of the basic charge carriers transport mechanisms at work. The dc and electrical noise characteristics of different polymer/carbon nanotubes composites have been analyzed from 10 to 300 K. The results suggest that all these systems can be regarded as random resistive networks of tunnel junctions formed by adjacent carbon nanotubes. However, in the high-temperature regime, contributions deriving from other possible mechanisms cannot be separated using dc information alone. A transition from a fluctuation-induced tunneling process to a thermally activated regime is instead revealed by electric noise spectroscopy. In particular, a crossover is found from a two-level tunneling mechanism, operating at low temperatures, to resistance fluctuations of a percolative network, in the high-temperature region. The observed behavior of 1/f noise seems to be a general feature for highly conductive samples, independent on the type of polymer matrix and on the nanotube density

Kondo-like transport and magnetic field effect of charge carrier fluctuations in granular aluminum oxide thin films

“…In this respect, electric noise spectroscopy has proved to be a very effective and efficient method for studying the kinetic processes of the charge carriers in several systems. As examples, it has strongly contributed to clarify unsolved fundamental questions regarding the electronic properties of manganites 10 , 11 , iron-based superconductors 12 , 13 , carbon nanotube composites 14 , and perovskite-based solar cells 15 . Moreover, the study and control of fluctuation mechanisms plays a crucial role to improve the efficiency of the future devices for quantum information processing 16 .…”

The effect of the nanotube oxidation on the rheological and electrical properties of CNT/HDPE nanocomposites

“…In the case of carbon nanotube loaded epoxy or polyethylene films, on the other hand, a strong temperature dependence of the electrical conductivity permits the realization of resistive temperature sensors, applicable over a wide temperature range. It should be noted that the identification of the physical mechanisms governing the particular temperature dependence of the electrical conductance in the case of highly MWNT loaded high density polyethylene (HDPE) and low density polyethylene (LDPE) samples, have been identified also by means of temperature‐dependent low frequency noise spectroscopy . In the field of bio‐nanocomposites, the use of carbon nanotubes has enabled the realization of new types of long‐term mechanical stability tissues, obtained from the combination of either fungal or plant cells with multi‐walled carbon nanotubes.…”

A noise model for the evaluation of defect states in solar cells

“…Subsequently, it was used for the reliability estimation of photovoltaic devices related to microplasma detection 5 , and of iron disilicide heterojunction solar cells 6 . More recently, the same tool was employed to evaluate transport properties and degradation processes in several other systems, such as organic light-emitting diodes 7 , polymer:fullerene solar cells 8 9 , bulk homogeneous semiconductors 10 11 , and polymer/carbon nanotube composites 12 .…”