Song Y M, Choi E S, Yu J S, Lee Y T
Department of Information and Communications, Gwangju Institute of Science and Technology, 1 Oryong-dong, Buk-gu, Gwangju 500-712, Republic of Korea.
Opt Express. 2009 Nov 9;17(23):20991-7. doi: 10.1364/OE.17.020991.
We demonstrate the enhancement of light extraction in 633 nm AlGaInP light-emitting diodes (LEDs) with antireflective subwavelength structures (SWS). From the contour plots by the rigorous coupled wave analysis method, it is found that the reduction of the internal reflection strongly depends on the period of SWS. The Ag nanoparticles formed by thermal dewetting were used as an etch mask for dry etch process to fabricate antireflective SWS on the LED surface. The tapered pillars on the GaP were fabricated, on average, with distances below 200 nm, satisfying the required antireflection condition at the emission wavelength. The improvement in light output power by approximately 26.4% was achieved for the fabricated AlGaInP LEDs with SWS compared to the conventional LEDs due to a strongly reduced Fresnel internal reflection at the GaP/air interface. The improved directionality in the far-field pattern was also obtained due to the directional light extraction enhancement.
我们展示了具有抗反射亚波长结构（SWS）的633 nm AlGaInP发光二极管（LED）中光提取的增强。通过严格耦合波分析方法得到的等高线图表明，内反射的减少强烈依赖于SWS的周期。通过热去湿形成的银纳米颗粒用作干法蚀刻工艺的蚀刻掩膜，以在LED表面制造抗反射SWS。在GaP上制造的锥形柱平均间距低于200 nm，满足发射波长处所需的抗反射条件。与传统LED相比，由于GaP/空气界面处的菲涅尔内反射大幅降低，制造的具有SWS的AlGaInP LED的光输出功率提高了约26.4%。由于定向光提取增强，还获得了远场图案中改善的方向性。
