Relative stability of excitonic complexes in quasi-one-dimensional semiconductors

TL;DR

This paper develops a configuration space approach to analyze the stability of excitonic complexes in quasi-one-dimensional semiconductors, revealing how confinement and material properties influence the relative stability of trions and biexcitons.

Contribution

It introduces a new theoretical framework to predict stability peculiarities of excitonic complexes in low-dimensional semiconductors.

Findings

Trions are more stable than biexcitons in strongly confined structures.

Biexcitons are more stable in less confined structures with larger reduced masses.

In carbon nanotubes, trion binding energy exceeds biexciton energy by about 40%.

Abstract

A configuration space approach is developed to uncover generic stability peculiarities for the lowest energy neutral and charged exciton complexes (biexciton and trion) in quasi-one-dimensional semiconductors. Trions are shown to be more stable than biexcitons in strongly confined structures with small reduced electron-hole masses. Biexcitons are more stable in less confined structures with large reduced electron-hole masses. In semiconducting carbon nanotubes, in particular, the trion binding energy is shown to be greater than that of the biexciton by a factor ~1.4 decreasing with diameter, thus revealing the general physical principles that underlie recent experimental observations.