Optical conductivity of one-dimensional narrow-gap semiconductors

TL;DR

This paper investigates the optical conductivity of one-dimensional narrow-gap semiconductors like quantum Hall edge states and carbon nanotubes, revealing how excitonic effects dominate at low energies and are suppressed at higher temperatures.

Contribution

It applies bosonization and renormalization group analysis to characterize the optical conductivity and excitonic effects in these semiconductors across different energy and temperature regimes.

Findings

Excitonic contributions dominate low-energy optical conductivity.

Thermal fluctuations eliminate excitonic features above a crossover temperature.

Crossover temperature for carbon nanotubes is estimated at 300 K.

Abstract

The optical conductivities of two one-dimensional narrow-gap semiconductors, anticrossing quantum Hall edge states and carbon nanotubes, are studied using bosonization method. A lowest order renormalization group analysis indicates that the bare band gap can be treated perturbatively at high frequency/temperature. At very low energy scale the optical conductivity is dominated by the excitonic contribution, while at temperature higher than a crossover temperature the excitonic features are eliminated by thermal fluctuations. In case of carbon nanotubes the crossover temperature scale is estimated to be 300 K.