Giant modulation of the electronic band gap of carbon nanotubes by dielectric screening

TL;DR

This study demonstrates that dielectric screening significantly reduces the electronic band gap in carbon nanotubes, revealing a controllable mechanism for tuning their electronic properties for advanced applications.

Contribution

The paper provides experimental evidence that dielectric environment manipulation can modulate the transport and band gaps of carbon nanotubes, highlighting a new approach for electronic property control.

Findings

25% reduction in transport gap when changing environment from air to isopropanol

32% reduction in band gap of narrow-gap CNTs with dielectric screening

Dielectric environment offers a mechanism for significant band gap control

Abstract

Carbon nanotubes (CNTs) are a promising material for high-performance electronics beyond silicon. But unlike silicon, the nature of the transport band gap in CNTs is not fully understood. The transport gap in CNTs is predicted to be strongly driven by electron-electron (e-e) interactions and correlations, even at room temperature. Here, we use dielectric liquids to screen e-e interactions in individual suspended ultra-clean CNTs. Using multiple techniques, the transport gap is measured as dielectric screening is increased. Changing the dielectric environment from air to isopropanol, we observe a 25% reduction in the transport gap of semiconducting CNTs, and a 32% reduction in the band gap of narrow-gap CNTs. Additional measurements are reported in dielectric oils. Our results elucidate the nature of the transport gap in CNTs, and show that dielectric environment offers a mechanism for significant control over the transport band gap.