Zero-Phonon Line Broadening and Satellite Peaks in Nanowire Quantum Dots: The Role of Piezoelectric Coupling

TL;DR

This study examines how the one-dimensional phonon modes in GaAs nanowires, especially piezoelectric interactions, affect the optical absorption spectrum of embedded quantum dots, revealing mode-specific spectral features.

Contribution

It demonstrates that piezoelectric coupling significantly influences axial phonon modes and absorption features, a novel insight into phonon-dot interactions in nanowires.

Findings

Piezoelectric coupling affects axial phonon modes and absorption peaks.

Zero-phonon line broadening is mainly due to acoustic phonons.

Piezoelectric interaction has negligible effect on the zero-phonon line.

Abstract

We investigate the influence of the one-dimensional character of the phonon modes in a catalytically grown GaAs nanowire on the absorption spectrum of an embedded quantum dot, focusing on the contribution from the piezoelectric coupling. In general, the reduced dimensionality of the phonons leads to spectral side peaks and a zero-phonon line broadening due to the energetically lowest (acoustic) phonon mode. While the deformation potential predominantly couples to radial modes, the piezoelectric interaction can also couple strongly to modes of axial character, leading to additional absorption features. The contribution of the piezoelectric coupling to the zero-phonon line is negligible.