自组装GaN/AlN量子点的单光子发射和复合动力学
Single photon emission and recombination dynamics in self-assembled GaN/AlN quantum dots
摘要：
III族氮化物量子点（QD）是一种有前途的系统，由于其在室温下保持单光子发射的能力而被积极研究。在这里，我们报告的演变的自组装GAN/AlN量子点的温度范围从5至300 K的发射性能。我们仔细地跟踪了单个量子点的光致发光，并在5 K和300 K下测量了g（2）（0）= 0.05 ± 0.02和0.17 ± 0.8的最佳单光子纯度。我们补充这项研究与温度相关的时间分辨的光致发光测量（TRPL）上进行的量子点系综，以进一步研究激子复合动力学的极性零维纳米结构。通过比较我们的结果与过去的报告，我们强调在这个系统中的重组过程的复杂性。而不是更传统的单指数衰减典型的激子复合，TRPL瞬变显示双指数的功能，持续在低激发制度的短寿命和长寿命的组件。从长寿命的激子组件的温度不敏感性，我们首先放弃了暗到亮的状态再填充激子复合过程中的相互作用。此外，这种温度不变性也突出了无辐射激子复合的存在，这可能是GAN/AlN量子点中观察到的高达300 K的强载流子限制的直接结果。总的来说，我们的研究结果支持这些点作为室温下量子应用的潜在单光子源的可行性。
英文摘要：
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.
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