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Abstract：
We study recombination processes in nitride LEDs emitting from 270 to 540 nm with EQE ranging from 4% to 70%. We found a significant correlation between the LEDs\' electro-optical properties and the degree of nanomaterial disorder (DND) in quantum wells (QWs) and heterointerfaces. DND depends on the nanoarrangement of domain structure, random alloy fluctuations, and the presence of local regions with disrupted alloy stoichiometry. The decrease in EQE values is attributed to increased DND and excited defect (ED) concentrations, which can exceed those of Shockley-Read-Hall defects. We identify two mechanisms of interaction between EDs and charge carriers that lead to a narrowing or broadening of electroluminescence spectra and increase or decrease EQE, respectively. Both mechanisms involve multiphonon carrier capture and ionization, impacting EQE reduction and efficiency droop. The losses caused by these mechanisms directly affect EQE dependencies on current density and the maximum EQE values for LEDs, regardless of the emission wavelength. Another manifestation of these mechanisms is the reversibility of LED degradation. Recombination processes vary depending on whether QWs are within or outside the space charge region of the p-n junction.
摘要：
我们研究了从270到540nm发射的氮化物LED中的复合过程，EQE范围从4％到70％。我们发现LED的电光特性与量子阱（QW）和异质界面中纳米材料无序（DND）的程度之间存在显着相关性。DND取决于域结构的纳米排列，随机合金波动，以及存在合金化学计量中断的局部区域。EQE值的下降归因于DND和激发缺陷（ED）浓度的增加，可以超过肖克利-阅读大厅的缺陷。我们确定了ED和电荷载流子之间相互作用的两种机制，这些机制导致电致发光光谱变窄或变宽，并增加或减少EQE。分别。这两种机制都涉及多声子载流子捕获和电离，影响EQE降低和效率下降。由这些机制引起的损耗直接影响EQE对电流密度的依赖性和LED的最大EQE值。无论发射波长。这些机制的另一种表现是LED退化的可逆性。重组过程取决于QW是在p-n结的空间电荷区域之内还是之外而变化。
