Temperature and Gas-Environment Dependent Electron and Phonon Transport in Suspended Carbon Nanotubes Up to Electrical Breakdown

TL;DR

This study investigates how temperature and gas environments influence electron and phonon transport in suspended carbon nanotubes, revealing temperature-dependent phonon behavior and gas-assisted phonon relaxation affecting electrical breakdown.

Contribution

It provides new insights into the temperature and gas environment effects on phonon transport and breakdown mechanisms in suspended carbon nanotubes.

Findings

Acoustic phonon thermal conductivity follows ~1/T at high temperatures.

Gas molecules facilitate relaxation of hot optical phonons, enhancing current.

High bias breakdown in vacuum involves melting due to hot optical phonons.

Abstract

High bias electrical transport characteristics of freely suspended metallic single-walled carbon nanotubes (SWNTs) are investigated at 250-400K in vacuum and various gases. Self-heating is exploited to examine the temperature dependence of phonon transport and optical phonon decay in SWNTs. The acoustic phonon thermal conductivity of a SWNT follows ~1/T at high temperatures. Non-equilibrium optical phonon effects in suspended nanotubes decrease as the ambient temperature increases. Gas molecules assist the relaxation of hot optical phonons along the tube length and enable enhanced current flow. In vacuum, high bias breakdown of suspended SWNTs can occur via melting caused by electrically emitted hot optical phonons at a low acoustic phonon temperature.