Optical recombination of biexcitons in semiconductors

TL;DR

This paper calculates the photoluminescence spectrum and lifetime of biexcitons in semiconductors using Quantum Monte Carlo methods, providing insights into recombination processes and effects of quantum confinement.

Contribution

It introduces a detailed computational approach for biexciton recombination, including quantum dot confinement effects, and offers benchmark data for future studies.

Findings

Surviving exciton tends to be in the ground state for certain hole masses.

Calculated lifetimes agree with experimental data.

Quantum confinement modifies biexciton lifetime in quantum dots.

Abstract

We calculate the photoluminescence spectrum and lifetime of a biexciton in a semiconductor using Fermi's golden rule. Our biexciton wavefunction is obtained using a Quantum Monte Carlo calculation. We consider a recombination process where one of the excitons within the biexciton annihilates. For hole masses greater than or equal to the electron mass, we find that the surviving exciton is most likely to populate the ground state. We also investigate how the confinement of excitons in a quantum dot would modify the lifetime in the limit of a large quantum dot where confinement principally affects the centre of mass wavefunction. The lifetimes we obtain are in reasonable agreement with experimental values. Our calculation can be used as a benchmark for comparison with approximate methods.