Indium gallium nitride quantum dots: Consequence of random alloy fluctuations for polarization entangled photon emission

TL;DR

This study investigates how random alloy fluctuations in InGaN/GaN quantum dots affect their symmetry and suitability for high-temperature polarization entangled photon emission, highlighting challenges and potential alternative schemes.

Contribution

It provides an atomistic analysis of alloy fluctuation effects on quantum dot symmetry and entangled photon emission potential, revealing symmetry loss impacts.

Findings

Random alloy fluctuations preserve excitonic binding energies.

Alloy fluctuations significantly disrupt $C_{3v}$ symmetry.

Symmetry loss negatively affects polarization entangled photon emission.

Abstract

We analyze the potential of the $c$-plane InGaN/GaN quantum dots for polarization entangled photon emission by means of an atomistic many-body framework. Special attention is paid to the impact of random alloy fluctuations on the excitonic fine structure and the excitonic binding energy. Our calculations show that $c$-plane InGaN/GaN quantum dots are ideal candidates for high temperature entangled photon emission as long as the underlying $C_{3v}$-symmetry is preserved. However, when assuming random alloy fluctuations in the dot, our atomistic calculations reveal that while the large excitonic binding energies are only slightly affected, the $C_{3v}$ symmetry is basically lost due to the alloy fluctuations. We find that this loss in symmetry significantly impacts the excitonic fine structure. The observed changes in fine structure and the accompanied light polarization characteristics have a detrimental effect for polarization entangled photon pair emission via the biexciton-exciton cascade. Here, we also discuss possible alternative schemes that benefit from the large excitonic binding energies, to enable non-classical light emission from $c$-plane InGaN/GaN quantum dots at elevated temperatures.