Effects of Inclined Sidewall Structure With Bottom Metal Air Cavity on the Light Extraction Efficiency for AlGaN-Based Deep Ultraviolet Light-Emitting Diodes
Effects of Inclined Sidewall Structure With Bottom Metal Air Cavity on the Light Extraction Efficiency for AlGaN-Based Deep Ultraviolet Light-Emitting Diodes
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DOI：
10.1109/jphot.2017.2736642
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发表时间：
2017-08
影响因子：
2.4
通讯作者：
Yonghui Zhang;Ruilin Meng;Zi-hui Zhang;Qiang Shi;Luping Li;Guoxu Liu;W. Bi
中科院分区：
文献类型：
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作者：
Yonghui Zhang;Ruilin Meng;Zi-hui Zhang;Qiang Shi;Luping Li;Guoxu Liu;W. Bi
为了提高AlGaN基深紫外发光二极管（DUV LED）的光提取效率（LEE），提出了一种倾斜侧壁散射结构。三维时域有限差分模拟结果表明，与已报道的侧壁金属倾斜侧壁（Sidewall_metal）结构相比，Bottom_metal结构可以显著提高深紫外LED的LEE。进一步分析表明，空气腔的存在促使Bottom_metal深紫外LED主要利用全内反射和菲涅耳散射将光散射到逃逸锥中，避免了侧壁金属结构中侧壁金属镜对光的吸收。此外，具有底部金属的独特空气腔还增强了Bottom_metal DUV LED的散射能力，因为腔体内指向下的任何光将被反射回来，并且空气腔/AlGaN的平行顶部界面用作不受全内反射限制的附加出光平面。
An inclined sidewall scattering structure with air cavity characterized by a metal bottom and flat parallel top (Bottom_metal) is proposed to enhance the light extraction efficiency (LEE) for AlGaN-based deep ultraviolet light-emitting diodes (DUV LEDs). Compared to the reported sidewall metal inclined sidewall (Sidewall_metal) structure, the Bottom_metal structure can greatly enhance the LEE of DUV LEDs based on three-dimensional finite difference time domain simulations. Further analysis indicates that the existence of the air cavity promotes the Bottom_metal DUV LEDs to mainly utilize the total internal reflection and the Fresnel scattering to scatter the light into the escape cone, which avoids the light absorption from the sidewall metal mirror in the Sidewall_metal structure. Moreover, the unique air cavity having a bottom metal also enhances the scattering ability of the Bottom_metal DUV LEDs because any light within the cavity directing downward will be reflected back, and the parallel top interface of air cavity/AlGaN functions as additional out-light planes not limited by total internal reflection.