Hot Phonon Bottlenecks and the Role of Non-Equilibrium Acoustic Phonons in III-V Multi-Quantum Well Systems

TL;DR

This paper advances the understanding of hot phonon bottlenecks in III-V multi-quantum well systems by modeling the build-up of acoustic phonons, leading to better explanations of experimental results and new pathways for hot carrier solar cells.

Contribution

It extends existing models by including acoustic phonon build-up, removing nonphysical assumptions, and improving the explanation of experimental observations.

Findings

Inclusion of acoustic phonons improves model accuracy.

Better explanation of experimental data.

Potential new approaches for high-temperature carrier generation.

Abstract

The hot phonon bottleneck effect is a promising mechanism for the realization of a true hot carrier solar cell. Prior work has assumed that the acoustic phonons created via decay of polar longitudinal optical (LO) phonons are assumed to quickly leave the system or thermalize quickly due to multi-phonon processes. The present work furthers the models of previous work to include a build-up of longitudinal acoustic phonons in addition to LO phonons due via the Klemens process. By including this additional process, nonphysical assumptions concerning the LO anharmonic lifetime are no longer required, resulting in a better explanation of the experimental results, and pointing towards new approaches in achieving high carrier temperatures during photo-excitation.