Electrically driven thermal light emission from individual single-walled carbon nanotubes

TL;DR

This study demonstrates that individual suspended quasi-metallic single-walled carbon nanotubes emit visible and infrared light when electrically heated, revealing thermal emission properties and enabling probing of electronic temperature and phonons.

Contribution

It reveals thermal light emission from single quasi-metallic SWNTs under electrical bias, contrasting with previous non-radiative expectations for metallic nanotubes.

Findings

Light emission occurs in the negative differential conductance regime.

Emission peaks correspond to interband transitions.

Thermal emission enables probing of electronic temperature and phonons.

Abstract

Light emission from nanostructures exhibits rich quantum effects and has broad applications. Single-walled carbon nanotubes (SWNTs) are one-dimensional (1D) metals or semiconductors, in which large number of electronic states in a narrow range of energies, known as van Hove singularities, can lead to strong spectral transitions. Photoluminescence and electroluminescence involving interband transitions and excitons have been observed in semiconducting SWNTs, but are not expected in metallic tubes due to non-radiative relaxations. Here, we show that in the negative differential conductance regime, a suspended quasi-metallic SWNT (QM-SWNT) emits light due to joule-heating, displaying strong peaks in the visible and infrared corresponding to interband transitions. This is a result of thermal light emission in 1D, in stark contrast with featureless blackbody-like emission observed in large bundles of SWNTs or multi-walled nanotubes. This allows for probing of the electronic temperature and non-equilibrium hot optical phonons in joule-heated QM-SWNTs.