PSS侧壁弧度优化及对GaN基LED出光效率的影响

Radian Optimization of the Side-Wall of the PSS Pattern and Its Influence on the Light Extraction Efficiency of GaN-Based LEDs

为进一步提高基于图形化蓝宝石衬底(PSS)技术的氮化镓(GaN)基LED的出光效率,针对PSS微结构的侧壁弧度进行了优化设计。研究实验采用感应耦合等离子体(ICP)干法刻蚀技术,通过优化三氟甲烷(CHF3)和三氯化硼(BCl3)气体体积流量比,实现了对微结构侧壁弧度的有效调控。此外,对各种类型GaN基LED芯片的光学特性进行了测试表征,并结合蒙特卡罗光线追迹方法模拟了PSS微结构的侧壁弧度变化对LED轴向、侧面和总出光效率的影响。实验和理论模拟结果表明,微结构的侧壁弧度对LED出光效率有显著影响,当微结构侧壁中心到内接圆锥侧壁中心的距离为(150±10)nm时,LED的出光效率将进一步提高8.9%。

In order to further improve the light extraction efficiency of the GaN-based LED grown on the patterned sapphire substrates（PSS）,the radian of the side-wall of the PSS micro structure was designed and optimized.The radian of the side-wall for the PSS micro structure was controlled effectively by optimizing the gas volume flow ratio of CHF3 to BCl3during the inductively coupled plasma（ICP）dry etching process.Furthermore,the optical properties of the GaN-based LED chips grown on different types of PSS samples were tested and characterized.Additionally,the influence of the radian of the side-wall for the PSS micro structure on the axial direction,sidewall and total light extraction efficiency of the GaN-based LED was simulated by using Monte Carlo ray-tracing method.The experimental data and theoretical simulation results show that the radian of the side-wall for the micro structure has an significant effect on the light extraction efficiency of the GaN-based LED.When the distance between the side-wall center of the micro structure and the side-wall center of the inscribed cone is（150±10）nm,the light extraction efficiency can be further improved by 8.9% compared to that of the LED with the conventional PSS pattern.