Internal quantum efficiency drop induced by the heat generation inside of light emitting diodes （LEDs）

The reasons for low output power of AlGaInP Light Emitting Diodes (LEDs) have been analysed. LEDs with AlGaInP material have high internal but low external quantum efficiency and much heat generated inside especially at a large injected current which would reduce both the internal and external quantum efficiencies. Two kinds of LEDs with the same active region but different window layers have been fabricated. The new window layer composed of textured 0.5 μm GaP and thin Indium-Tin-Oxide film has shown that low external quantum efficiency (EQE) has serious impaction on the internal quantum efficiency (IQE), because the carrier distribution will change with the body temperature increasing due to the heat inside, and the test results have shown the evidence of LEDs with lower output power and bigger wavelength red shift.     

AlGaInP大功率发光二极管发光效率与结温的关系

目前,AlGaInP大功率发光二极管(LED)存在的主要问题是大电流工作时发热严重,主要是由于电流扩展不均匀、出光面电极对光子的阻挡和吸收以及器件材料与空气折射率之间的差距引起的全反射现象,这些因素造成大功率LED出光受到限制、发光效率低、亮度不高.提出了一种复合电流扩展层和复合分布式布拉格反射层(DBR)的新型结构LED,使得注入电流在有源区充分地扩散,同时提高了常规单DBR对光子的反射率.结果显示,这种新型结构LED比常规结构LED的性能得到了很大的提升,350 mA注入电流下两者的输出光功率分别为4 关键词： 复合电流扩展层 复合分布式布拉格反射层 出光效率 结温     

不同表面结构的半导体发光二极管的效率与寿命的研究

对GaAs基AlGaInP系半导体发光二极管（light emitting diode,LED）提取效率低导致器件发热而寿命缩短等问题进行了分析,提出了一种新型表面结构的LED,在与普通LED相同的外延生长条件下,通过后工艺引入了表面图形并腐蚀出凹凸不平的表面以改变光子传输方向,同时制备了导电光增透层,既增强了电流的扩展同时使得更多的光子能够发射到体外,在相同的注入电流下,新型表面增透结构LED的轴向光强平均是普通LED的15倍,由于光提取效率高,更多的光子能够发射到体外,发热减少,饱和电流更高,达到1 关键词： 表面增透结构 轴向光强 光效 寿命     

表面为二维光子晶体结构的AlGaInP系发光二极管的研究

近年来,GaN基光子晶体发光二极管(light emitting diode,LED)的研究已经取得了一定的进展,利用光子晶体的光子带隙效应和光栅衍射原理,在LED上制作光子晶体结构将会提高出光效率.本文为了提高AlGaInP系LED的光提取效率,分析了常规LED光提取效率受到限制的原因,将光子晶体结构引入了AlGaInP系LED的器件结构设计,通过理论分析与实验验证,结果显示:光子晶体结构对于提高AlGaInP系LED的光提取效率同样起到了明显的效果,引入光子晶体后,LED的输出光强比常规结构LED平均 关键词： AlGaInP系LED 光子晶体 光提取效率 光强     

新型AlGaInP系发光二极管饱和特性与寿命的研究

针对AlGaInP系发光二极管(LED)电极阻挡出光、衬底吸收、全反射角小导致器件出光效率低、热积累大、饱和特性差等问题,提出了一种具有复合电流输运增透窗口层、复合DBR反射镜和电流阻挡层结构的新型LED,并测试了其饱和特性和寿命.电流分布模拟显示:新型LED电极下仅存在极小的无效电流;实验结果表明新型LED出光效率高,饱和电流大,饱和电流时光强约为常规LED的3倍,光电性能明显提升.器件饱和特性和老化实验研究显示:新型LED寿命长达17.8×104h,器件内部发热量低,具有高饱和特性和高可靠性,适合在大电流大功率下工作.     

一种与光纤高效耦合的新型大光腔大功率半导体激光器

提出并实现了一种新型多有源区隧道级联大光腔半导体激光器，提高了激光器激射窗口的宽度，得到低于20°的垂直发散角，从而提高了光纤输出的耦合效率.对多种形式和规格的透镜光纤的测试结果表明，耦合效率可以提高30%以上. 关键词： 半导体激光器 大光腔 光纤耦合 透镜光纤     

AlGaInP-Si glue bonded high performance light emitting diodes

We propose a new method of using conductive glue to agglutinate GaAs based AlGaInP light emitting diodes (LEDs) onto silicon substrate,and the absorbing GaAs layer is subsequently removed by grinding and selective wet etching.It was found that AlGaInP-Si glue agglutinated LEDs have larger saturation current and luminous intensity than the conventional LEDs working at the same injected current.The luminous intensity of the new device is as much as 1007.4 mcd at a saturation current of 125 mA without being encapsulated,while the conventional LEDs only have 266.2 mcd at a saturation current of 105 mA.The luminescence intensity is also found to increase by about 3.2% after working at 50 mA for 768 h.This means that the new structured LEDs have good reliability performance.