Configuration space method for calculating binding energies of exciton complexes in quasi-1D/2D semiconductors

TL;DR

This paper introduces a configuration space method to calculate binding energies of exciton complexes in quasi-1D and 2D semiconductors, revealing how confinement affects their stability.

Contribution

It develops a universal approach for exciton complex binding energies in confined nanostructures and uncovers crossover behavior based on confinement and mass.

Findings

Trions have higher binding energy in strongly confined structures.

Biexcitons are more stable in less confined structures.

A universal crossover behavior between trion and biexciton stability is identified.

Abstract

A configuration space method is developed for binding energy calculations of the lowest energy exciton complexes (trion, biexciton) in spatially confined quasi-1D semiconductor nanostructures such as nanowires and nanotubes. Quite generally, trions are shown to have greater binding energy in strongly confined structures with small reduced electron-hole masses. Biexcitons have greater binding energy in less confined structures with large reduced electron-hole masses. This results in a universal crossover behavior, whereby trions become less stable than biexcitons as the transverse size of the quasi-1D nanostructure increases. The method is also capable of evaluating binding energies for electron-hole complexes in quasi-2D semiconductors such as coupled quantum wells and bilayer van der Walls bound heterostructures with advanced optoelectronic properties.