Efficiency and Forward Voltage of Blue and Green Lateral LEDs with V-shaped Defects and Random Alloy Fluctuation in Quantum Wells
Efficiency and Forward Voltage of Blue and Green Lateral LEDs with V-shaped Defects and Random Alloy Fluctuation in Quantum Wells
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DOI：
10.1103/physrevapplied.17.014033
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发表时间：
2022-01-25
影响因子：
4.6
通讯作者：
Wu, Yuh-Renn
中科院分区：
文献类型：
--
作者：
Ho, Cheng-Han;Speck, James S.;Wu, Yuh-Renn
对于氮基蓝色和绿色发光二极管（led），正向电压Vfor大于预期，特别是绿色led。这主要是由于在多个量子阱和量子势垒界面处的总极化不连续造成了垂直载流子输运的巨大障碍。量子阱中合金的自然随机涨落已被证明是减小Vfor的重要因素。然而，这在绿色led的情况下是不够的，因为它们的极化诱导势垒更大。v形缺陷（V-defects）被认为是降低v势的另一个关键因素，从而允许横向注入到多个量子井中，从而绕过垂直输运引起的多重能量势垒。在本文中，为了模拟整个LED中的载流子输运，我们考虑了随机合金效应和v缺陷效应。一个全二维漂移扩散电荷控制解算器用于模拟这两种效应。结果表明，蓝色和绿色led的导通电压均受随机合金波动和v缺陷密度的影响。对于绿色led，由于v型缺陷，Vfor降低更多，其中v型缺陷侧壁较小的极化势垒是横向载流子注入的主要途径。最后讨论了v型缺陷密度和尺寸对结果的影响。
For nitride-based blue and green light-emitting diodes (LEDs), the forward voltage Vfor is larger than expected, especially for green LEDs. This is mainly due to the large barriers to vertical carrier transport caused by the total polarization discontinuity at multiple quantum well and quantum barrier interfaces. The natural random alloy fluctuation in quantum wells has proven to be an important factor reducing Vfor. However, this does not suffice in the case of green LEDs because of their larger polarization-induced barrier. V-shaped defects (V-defects) have been proposed as another key factor in reducing Vfor to allow lateral injection into multiple quantum wells, thus bypassing the multiple energy barriers incurred by vertical transport. In this paper, to model carrier transport in the whole LED, we consider both random alloy and V-defect effects. A fully two-dimensional drift-diffusion charge-control solver is used to model both effects. The results indicate that the turn-on voltages for blue and green LEDs are both affected by random alloy fluctuations and the V-defect density. For green LEDs, Vfor decreases more due to V-defects, where the smaller polarization barrier at the V-defect sidewall is the major path for lateral carrier injection. Finally, we discuss how the V-defect density and size affects the results.