一种基于表面微结构提高LED光提取率的方法

Study on enhancement of light extraction efficiency for surface microstructure-based light-emitting diode

针对提高发光二极管(LED)光提取率问题,利用LED的发光和表面等离子原理,采用严密耦合波计算方法,在LED表面添加金属周期性亚波长微结构,使表面等离子体耦合的逆过程向另一侧低折射率介质(空气)中辐射出可见光,可增加入射光提取。对不同周期的金属微结构进行模拟,结果表明,金属表面薄膜厚度对表面等离子体产生的影响在临界角25～40°范围内,微结构不仅使表面等离子再次耦合为透射光,而且还增大了共振峰的深度与宽度。

A method of improving extraction rate of light emitting diode （LED） light is introduceal based on the micro-structure. By adopting rigorous coupled-wave calculation according to the LED structure of its sparkle principle and surface plasma principle, the result is obtaened that when visible light encountered the surface of GaN LEDs with the periodic sub wavelength metal microstructure, it would couple into the metal surface and become surface plasma. Then the surface plasma on the metal surface would couple, by an inverse process back to the other side of the low refractive index medium （air） as visible light radiation, and therefore wide-angle incident light in the GaN could be extracted. How the film thickness on the dielectric surface affects the generation of surface plasma is discussed and then the surfaces of the LED with different periods microstructure of metal are simulated. With critical angle between 25°to 40°, the microstrueture not only makes surface plasma coupling into transmission light again, but also increases the depth and width of peak.