# Mapping defect distribution in transparent single-walled carbon nanotube film with electrical resistance tomography

## TL;DR

This paper introduces a new method using electrical resistance tomography to map defects in transparent carbon nanotube films, enabling non-destructive quality evaluation.

## Contribution

The novel use of ERT to convert conductivity into IG/ID maps for defect detection in SWCNT films.

## Key findings

- ERT successfully detected a defect region with an IG/ID ratio of 15 in a pristine SWCNT film (IG/ID = 18.1).
- ERT distinguished two defect regions with a small IG/ID ratio difference of 1.1 caused by plasma irradiation.
- Simulation studies identified electrode misalignment and contact resistance as causes of image deviations.

## Abstract

We extend the application of electrical resistance tomography (ERT) to visualize IG/ID distribution in transparent single-walled carbon nanotube (SWCNT) thin films. By establishing the correlation between disorder and resistance through experimental measurements, we successfully converted ERT-reconstructed conductivity distributions into IG/ID maps. This approach enabled the detection of a defect region with an IG/ID ratio of approximately 15 embedded in a pristine SWCNT film (IG/ID = 18.1), corresponding to a minimum detectable resistance ratio (R/R0) of 1.59. Moreover, in a sample containing two defect regions introduced by plasma irradiation at 20 and 40 W, ERT successfully distinguished them despite the small difference in IG/ID ratio (1.1). Simulation studies revealed that positional deviations in reconstructed images can be attributed to electrode misalignment, contact resistance variation, and plasma-induced defect expansion. These results demonstrate the feasibility of ERT as a non-destructive, high-resolution technique for evaluating disorder variations in conductive thin films. Furthermore, due to its conductivity-based imaging principle, the method is applicable to other materials such as graphene, indium tin oxide (ITO), and metal nanowire networks, offering promise for real-time monitoring and quality assurance in large-area optoelectronic device manufacturing.

The online version contains supplementary material available at 10.1038/s41598-025-29839-w.