Single photon emission and recombination dynamics in self-assembled GaN/AlN quantum dots

TL;DR

This study investigates the emission and recombination dynamics of GaN/AlN quantum dots across a wide temperature range, demonstrating their potential as stable room-temperature single-photon sources for quantum technologies.

Contribution

It provides detailed temperature-dependent photoluminescence and TRPL analysis, revealing complex bi-exponential recombination processes and confirming strong carrier confinement in GaN/AlN QDs.

Findings

High single photon purity at room temperature (g(2)(0)=0.17)

Bi-exponential exciton recombination dynamics

Absence of nonradiative recombination up to 300K

Abstract

III-nitride quantum dots (QDs) are a promising system actively studied for their ability to maintain single photon emission up to room temperature. Here, we report on the evolution of the emission properties of self-assembled GaN/AlN QDs for temperatures ranging from 5 to 300K. We carefully track the photoluminescence of a single QD and measure an optimum single photon purity of g(2)(0) = 0.05+-0.02 at 5 K and 0.17+-0.8 at 300 K. We complement this study with temperaturedependent time-resolved photoluminescence measurements (TRPL) performed on a QD ensemble to further investigate the exciton recombination dynamics of such polar zero-dimensional nanostructures. By comparing our results to past reports, we emphasize the complexity of recombination processes in this system. Instead of the more conventional mono-exponential decay typical of exciton recombination, TRPL transients display a bi-exponential feature with short- and long-lived components that persist in the low excitation regime. From the temperature insensitivity of the long-lived excitonic component, we first discard the interplay of dark-to-bright state refilling in the exciton recombination process. Besides, this temperature-invariance also highlights the absence of nonradiative exciton recombinations, a likely direct consequence of the strong carrier confinement observed in GaN/AlN QDs up to 300K. Overall, our results support the viability of these dots as a potential single-photon source for quantum applications at room temperature.