Department of Materials Science and Engineering, Korea University, 5-1 Anam-dong, Sungbuk-gu, Seoul 136-713, South Korea.
Opt Lett. 2011 Aug 15;36(16):3203-5. doi: 10.1364/OL.36.003203.
Distributed antireflection (AR) layers with different composition ratios of ITO and SiO(2) formed on an ITO electrode of GaN-based LEDs provide substantial enhancement in light-extraction efficiency. By using the coradio frequency magnetron sputtering deposition, four 50 nm thick AR layers with graduated refractive indices were fabricated. The effect of the AR layers on enhancing the efficiency of the LED device was analyzed by electroluminescence (EL) and I-V measurements. As a result, the EL intensity of the LED device grown on the patterned sapphire substrate with AR layers was increased by up to 13% compared to the conventional patterned sapphire substrate-applied LED device without AR layers at a drive current of 20 mA. The AR layers on top of the LED device gradually changed the refractive indices between ITO (n=2.1) and air (n=1.0), which minimized the total internal reflection of generated light. And no degradation in the electrical characteristic of the LEDs was observed according to the I-V measurements.
在 GaN 基 LED 的 ITO 电极上形成具有不同 ITO 和 SiO2 组成比例的分布式抗反射 (AR) 层可显著提高光提取效率。通过使用共射频磁控溅射沉积，制备了四个具有不同折射率的 50nm 厚的 AR 层。通过电致发光 (EL) 和 I-V 测量分析了 AR 层对提高 LED 器件效率的影响。结果表明，与没有 AR 层的常规图案化蓝宝石衬底应用 LED 器件相比，在 20mA 的驱动电流下，生长在具有 AR 层的图案化蓝宝石衬底上的 LED 器件的 EL 强度增加了 13%。LED 器件顶部的 AR 层逐渐改变了 ITO（n=2.1）和空气（n=1.0）之间的折射率，从而最大程度地减少了产生光的全内反射。根据 I-V 测量，没有观察到 LED 电特性的退化。
