Impact Excitation by Hot Carriers in Carbon Nanotubes

TL;DR

This paper theoretically examines how hot carriers induce impact excitation in carbon nanotubes, revealing enhanced efficiencies due to electron confinement, excitonic effects, and phonon interactions, with implications for nanoscale optoelectronics.

Contribution

It provides a detailed theoretical analysis of impact excitation mechanisms in carbon nanotubes, highlighting the roles of excitonic coupling and phonon effects, which were less understood before.

Findings

Enhanced excitation efficiency due to electron confinement and reduced screening.

Strong excitonic coupling favors neutral excitations over ionization.

Impact excitation rate depends on optical phonon excitation and field strength.

Abstract

We investigate theoretically the efficiency of intra-molecular hot carrier induced impact ionization and excitation processes in carbon nanotubes. The electron confinement and reduced screening lead to drastically enhanced excitation efficiencies over those in bulk materials. Strong excitonic coupling favors neutral excitations over ionization, while the impact mechanism populates a different set of states than that produced by photoexcitation. The excitation rate is strongly affected by optical phonon excitation and a simple scaling of the rate with the field strength and optical phonon temperature is obtained.