Chemical etching and Al2O3 dielectric passivation were used to minimize nonradiative sidewall defects in InGaN/GaN microLEDs (mesa diameter = 2–100 μm), resulting in an increase in external quantum efficiency (EQE) as the LED size was decreased. Peak EQEs increased from 8%–10% to 12%–13.5% for mesa diameters from 100 μm to 2 μm, respectively, and no measurable leakage currents were seen in current density–voltage (J–V) characteristics. The position and shape of EQE curves for all devices were essentially identical, indicating size-independent ABC model (Shockley–Read–Hall, radiative, and Auger recombination) coefficients-behavior that is not typical of microLEDs as the size decreases. These trends can be explained by enhancement in light extraction efficiency (LEE), which is only observable when sidewall defects are minimized, for the smallest LED sizes. Detailed ray-tracing simulations substantiate the LEE enhancements.

中文翻译：

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通过化学处理和介电钝化揭示 InGaN/GaN microLED 中光提取效率的重要性

化学蚀刻和 Al2O3 电介质钝化用于最大限度地减少 InGaN/GaN microLED（台面直径 = 2-100 μm）中的非辐射侧壁缺陷，随着 LED 尺寸的减小，导致外部量子效率 (EQE) 增加。对于 100 μm 至 2 μm 的台面直径，峰值 EQE 分别从 8%–10% 增加到 12%–13.5%，并且在电流密度-电压 (J-V) 特性中未观察到可测量的漏电流。所有器件的 EQE 曲线的位置和形状基本相同，表明随着尺寸减小，与尺寸无关的 ABC 模型（Shockley-Read-Hall、辐射和俄歇复合）系数行为不是 microLED 的典型特征。这些趋势可以通过光提取效率 (LEE) 的提高来解释，这只有在侧壁缺陷最小化时才能观察到，用于最小的 LED 尺寸。详细的光线追踪模拟证实了 LEE 的增强。