正方形孔径纳米半球阵列提高LED光提取效率研究

为提高氮化镓(Ga N)基发光二极管(LED)的光提取效率,基于等效介质理论设计了底面100%占空比、半径为320 nm的正方形孔径纳米半球阵列。利用时域有限差分法(FDTD)对正方形孔径纳米半球阵列结构底面占空比、半径对光提取效率的影响进行了仿真计算研究。仿真结果表明:LED p-Ga N表面刻蚀半径为320 nm、底面占空比为100%的正方形孔径纳米半球阵列的光提取效率最优。采用电子束曝光配合热回流技术和ICP刻蚀完成正方形孔径纳米半球阵列的Ga N基LED制作及测试实验。结果表明:在20 m A和150 m A工作电流下,有微纳结构的LED较无微纳结构的参考样品的发光效率分别提高4.67倍和4.59倍,计算结果与实验结果比较一致,说明加入方形孔径纳米半球阵列可以有效提高LED光提取效率。

Study of Light Extraction Efficiency for LED with Square Aperture Nano-hemisphere Array

Based on the equivalent medium theory, an square aperture nano-hemisphere structure with bottom surface fill-factor of 100% and spherical vector height of 320 nm was designed and put into use in the course of experiment as it sought to make GaN-based LED more efficient. Guided by the finite-difference time-domain method ( FDTD ) , a simulation research on how the parameters of structure influenced the light extraction efficiency performance, such as the spherical vector height, the bottom surface fill-factor was schemed to be conducted in the experiment. The study provided the evidence that the optical light extraction efficiency could be achieved on the occasion that the square aperture nano-hemisphere array with a radius of 320 nm and a bottom surface fill-factor 100% p-GaN was etched and presented on the surface of LED. Such technologies as electron beam exposure combined with thermal reflow and ICP etching should be applied and come into service for building square aperture nano-hemisphere arrays. In strict accordance with calculation results, under the working current of 20 mA and 150 mA, the luminous efficiency of the LED with the nano structure is 4. 67 times and that of the reference sample is less than 4. 59 times, which shows that square aper-ture nano-hemisphere array promises to help make the light extraction efficiency of LED better, ac-cording to the electroluminescence test.