For high-power applications, it is important to improve the light extraction efficiency and light output of the vertical direction of LEDs. Flip-chip LEDs (FCLEDs) with an Ag/SiO₂/distributed Bragg reflector/SiO₂ composite reflection micro structure (CRS) were fabricated. Compared with the normal Ag-based FCLEDs, the light output power of the CRS-FCLEDs was increased by 6.3% at an operational current of 1500 mA, with the corresponding external quantum efficiency improved by 6.0%. Further investigation proved that the CRS structure exhibited higher reflectance compared with the commonly used Ag-mirror reflective structure, which originates from the increased reflective area in the sidewall and partial area of the n-GaN contact orifices. It exhibited markedly smaller optical degradation and thus higher device reliability as compared to normal Ag-based FCLED. Moreover, the light emission intensity distributions and far-field angular light emission measurements show that the CRS-FCLED has a strengthened light output in the vertical direction, which shows great potential for applications in high-power fields, such as headlamps for automobiles.

中文翻译：

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利用侧壁复合反射微结构提高大功率氮化镓基倒装芯片 LED 的外量子效率

对于大功率应用，提高LED垂直方向的光提取效率和光输出很重要。具有 Ag/SiO ₂ /分布式布拉格反射器/SiO _{2 的}倒装芯片 LED (FCLED)复合反射微结构（CRS）。与普通银基FCLED相比，CRS-FCLED在1500 mA工作电流下的光输出功率提高了6.3%，相应的外量子效率提高了6.0%。进一步研究证明，与常用的Ag镜反射结构相比，CRS结构表现出更高的反射率，这源于n-GaN接触孔的侧壁和部分区域的反射面积增加。与普通的基于银的 FCLED 相比，它表现出明显更小的光学退化，因此具有更高的器件可靠性。此外，发光强度分布和远场角发光测量表明，CRS-FCLED在垂直方向具有增强的光输出，