Radiative recombination mechanisms in polar and non-polar InGaN/GaN quantum well LED structures
Radiative recombination mechanisms in polar and non-polar InGaN/GaN quantum well LED structures
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DOI：
10.1063/1.4964842
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发表时间：
2016-10-10
影响因子：
4
通讯作者：
Shields, A. J.
中科院分区：
文献类型：
--
作者：
Badcock, T. J.;Ali, M.;Shields, A. J.
研究了一对极性和非极性InGaN/GaN量子阱(QW)发光二极管(LED)结构的光致发光内量子效率(IQE)和复合动力学随过量载流子浓度和温度的变化。在293K的极化LED中，辐射寿命和非辐射寿命的变化可以用修正的ABC型模型很好地描述，该模型考虑了非故意掺杂引起的量子阱中的本底载流子浓度。随着温度的降低，辐射寿命对过量载流子密度的敏感性逐渐减弱。我们将这种行为归因于低温下定域电子和空穴的迁移率降低，导致了更多单分子的辐射过程。因此，我们认为在极性量子阱中，载流子的局域化程度决定了辐射寿命对过量载流子密度的敏感性。在非极性LED中，辐射寿命与室温下的激发密度无关，符合完全激子复合机制。这些发现对于在ABC重组模型的背景下解释LED效率数据具有重要意义。由AIP出版公司出版。
We study the photoluminescence internal quantum efficiency (IQE) and recombination dynamics in a pair of polar and non-polar InGaN/GaN quantum well (QW) light-emitting diode (LED) structures as a function of excess carrier density and temperature. In the polar LED at 293 K, the variation of radiative and non-radiative lifetimes is well described by a modified ABC type model which accounts for the background carrier concentration in the QWs due to unintentional doping. As the temperature is reduced, the sensitivity of the radiative lifetime to excess carrier density becomes progressively weaker. We attribute this behaviour to the reduced mobility of the localised electrons and holes at low temperatures, resulting in a more monomolecular like radiative process. Thus we propose that in polar QWs, the degree of carrier localisation determines the sensitivity of the radiative lifetime to the excess carrier density. In the non-polar LED, the radiative lifetime is independent of excitation density at room temperature, consistent with a wholly excitonic recombination mechanism. These findings have significance for the interpretation of LED efficiency data within the context of the ABC recombination model. Published by AIP Publishing.