Stachurski Johann, Tamariz Sebastian, Callsen Gordon, Butté Raphaël, Grandjean Nicolas
Institute of Physics, École Polytechnique Fédérale de Lausanne, EPFL, CH-1015, Lausanne, Switzerland.
Université Côte d'Azur, CNRS, CRHEA, F-06560, Valbonne, France.
Light Sci Appl. 2022 Apr 28;11(1):114. doi: 10.1038/s41377-022-00799-4.
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 300 K. We carefully track the photoluminescence of a single QD and measure an optimum single photon purity of g(0) = 0.05 ± 0.02 at 5 K and 0.17 ± 0.08 at 300 K. We complement this study with temperature dependent 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 300 K. Overall, our results support the viability of these dots as a potential single-photon source for quantum applications at room temperature.
III族氮化物量子点（QDs）是一个很有前景的体系，因其在室温下仍能保持单光子发射的能力而受到积极研究。在此，我们报告了自组装GaN/AlN量子点在5至300 K温度范围内发射特性的演变。我们仔细跟踪单个量子点的光致发光，并测量了在5 K时g(0) = 0.05 ± 0.02以及在300 K时g(0) = 0.17 ± 0.08的最佳单光子纯度。我们通过对量子点集合进行温度相关的时间分辨光致发光测量（TRPL）来补充这项研究，以进一步研究这种极性零维纳米结构的激子复合动力学。通过将我们的结果与过去的报告进行比较，我们强调了该系统中复合过程的复杂性。与激子复合中更常见的单指数衰减不同，TRPL瞬态显示出双指数特征，具有在低激发态下持续存在的短寿命和长寿命成分。从长寿命激子成分对温度不敏感这一点来看，我们首先排除了激子复合过程中暗态到亮态再填充的相互作用。此外，这种温度不变性还突出了无辐射激子复合的不存在，这很可能是在高达300 K的GaN/AlN量子点中观察到的强载流子限制的直接结果。总体而言，我们的结果支持了这些量子点作为室温量子应用潜在单光子源的可行性。
