Transport and Photo-Conduction in Carbon Nanotube Fibers

TL;DR

This study investigates the electrical conductivity of semiconducting carbon nanotube fibers under varying temperatures and laser irradiation, revealing fluctuation-induced tunneling as the dominant conduction mechanism and demonstrating laser-induced conductivity enhancement.

Contribution

It provides a detailed analysis of conduction mechanisms in CNT fibers and confirms the fluctuation induced tunneling model through experimental and simulation data.

Findings

Conductivity follows Arrhenius law at high temperatures.

Fluctuation induced tunneling explains conduction from room temperature to 4.2 K.

Laser irradiation enhances fiber conductivity without significant heating effects.

Abstract

We have characterized the conductivity of carbon nanotubes (CNT) fibers enriched in semiconducting species as a function of temperature and pulsed laser irradiation of 266 nm wavelength. While at high temperatures the response approaches an Arrhenius law behavior, from room temperature down to 4.2 K the response can be framed, quantitatively, within the predictions of the fluctuation induced tunneling which occurs between the inner fibrils (bundles) of the samples and/or the elementary CNTs constituting the fibers. Laser irradiation induces an enhancement of the conductivity, and analysis of the resulting data confirms the (exponential) dependence of the potential barrier upon temperature as expected from the fluctuation induced tunneling model. A thermal map of the experimental configuration consisting of laser-irradiated fibers is also obtained via COMSOL simulations in order to rule out bare heating phenomena as the background of our experiments. (*) Author