Spectral broadening in self-assembled GaAs quantum dots with narrow size distribution

TL;DR

This paper demonstrates a self-assembly method to produce strain-free GaAs quantum dots with very narrow size distribution, resulting in reduced spectral broadening and enabling detailed phonon broadening analysis over a wide temperature range.

Contribution

A novel self-assembly approach to create strain-free GaAs quantum dots with less than 15% size variation, leading to narrow emission linewidths and improved spectral control.

Findings

Quantum dots exhibit a 19 meV linewidth at 14 K.

Narrow emission band due to controlled size distribution.

Ability to analyze phonon broadening across temperatures.

Abstract

The control over the spectral broadening of an ensemble of emitters, mainly attributable to the size and shape dispersion and the homogenous broadening mechanisms, is crucial to several applications of quantum dots. We present a convenient self-assembly approach to deliver strain-free GaAs quantum dots with size distribution below 15%, due to the control of the growth parameters during the preliminary formation of the Ga droplets. This results in an ensemble photoluminescence linewidth of 19 meV at 14 K. The narrow emission band and the absence of a wetting layer promoting dot-dot coupling allow us to deconvolve the contribution of phonon broadening in the ensemble photoluminescence and study it in a wide temperature range.