# Enhanced Tunnelling in a Hybrid of Single-Walled Carbon Nanotubes and Graphene

## TL;DR

This paper demonstrates that using graphene as a substrate significantly enhances charge tunneling in SWCNT networks, reducing sheet resistance and improving conductivity without altering nanotube spectral features, especially when combined with doping.

## Contribution

It introduces a hybrid approach using graphene substrates to improve tunneling efficiency in SWCNT networks, achieving lower sheet resistance at high transmittance.

## Key findings

- Graphene substrate reduces tunneling barrier heights in SWCNT networks.
- Sheet resistance decreases by over 50% on graphene compared to other substrates.
- Combining graphene and $ ext{AuCl}_3$ doping yields sheet resistance as low as 36 Ω/sq at 90% transmittance.

## Abstract

Transparent and conductive films (TCFs) are of great technological importance. The high transmittance, electrical conductivity and mechanical strength make single-walled carbon nanotubes (SWCNTs) a good candidate for their raw material. Despite the ballistic transport in individual SWCNTs, however, the electrical conductivity of their networks is limited by low efficiency of charge tunneling between the tube elements. Here, we demonstrate that the nanotube network sheet resistance at high optical transmittance is decreased by more than 50% when fabricated on graphene and thus provides a comparable improvement as widely adopted gold chloride ($\mathrm{AuCl_3}$) doping. However, while Raman spectroscopy reveals substantial changes in spectral features of doped nanotubes, no similar effect is observed in presence of graphene. Instead, temperature dependent transport measurements indicate that graphene substrate reduces the tunneling barrier heights while its parallel conductivity contribution is almost negligible. Finally, we show that combining the graphene substrate and $\mathrm{AuCl_3}$ doping, the SWCNT thin films can exhibit sheet resistance as low as 36 $\Omega$/sq. at 90% transmittance.