垂直结构GaN基LED用Ni/Ag反射镜电极  

Ni/Ag Reflector Electrode of GaN-Based Vertical LED

作　　者：卜庆典 周伦茂 龙浩[1] 应磊莹[1] 郑志威[1] 张保平[1] 

机构地区：[1]厦门大学信息科学与技术学院,福建厦门361005

出　　处：《半导体技术》2017年第8期591-597,共7页Semiconductor Technology

基　　金：国家自然科学基金委联合基金资助项目(U1505253);国家重点研发计划战略性电子材料重点专项资助项目(2016YFB0400800);广东省科技重大专项资助项目(2014B010119004)

摘　　要：Ni/Ag/Ti/Au金属系反射镜电极广泛用于GaN基垂直结构发光二极管(LED)的传统制造工艺。这种电极需要进行高温长时间整体退火才能获得高质量的欧姆接触,但对电极的反射率和器件性能影响较大。介绍了一种新工艺方法,该方法将电极分解为接触层和反射层,降低反射层经历的退火温度和时间,获得了拥有良好的欧姆接触特性和高反射率的反射镜电极,解决了传统电极光学性能和电学性能相互制约的问题。首先生长极薄的Ni/Ag作为接触层,对接触层进行高温长时间退火后再生长厚层Ag作为反射层,之后再进行一次低温退火。使得对反射起主要作用的反射层免于高温长时间退火,相较于传统Ni/Ag/Ti/Au电极,该方法在获得更优良的欧姆接触的同时,提升了电极的反射率。在氧气氛围下进行500℃接触层退火3 min,400℃整体退火1 min后,电极的比接触电阻率为1.7×10^(-3)Ω·cm^2,同时在450 nm处反射率为93%。The Ni/Ag/Ti/Au metal reflector electrode is widely used in the GaN-based vertical structured light-emitting diode（ LED）,traditional fabrication process. However,the formation of ohmic contact with high quality needs a high temperature and long time annealing,which deteriorates the reflectivity of the reflector and the performance of the device. A new method based on the concept of decoupling the reflector electrode into a contact layer and a reflection layer was introduced,and the annealing time and the temperature were reduced by this method. The reflector electrode with good ohmic contact characteristics and high reflectivity was obtained,which solved the problem that the optical and electrical properties of the conventional electrode were mutually restricted. Firstly,an extremely thin Ni/Ag contact layer was deposited as the contact layer. After long-time annealing with high temperature for the contact layer,the thick layer Ag metal was deposited as the reflecting layer,then followed by a low temperature annealing. In the above process,the refecting layer,which plays a major role in the reflection,is free from high temperature and long time annealing. Compared with the traditional Ni/Ag/Ti/Au electrode,the method achieves better ohmic contact and greatly improves the reflectivity of the electrode. After annealing of the contact layer at 500 ℃ for 3 min and annealing of the whole structure at 400 ℃ for 1 min,both in oxygen atmosphere,the specific contact resistivity of the electrode reaches 1. 70×10^-3Ω·cm^2 and the reflectivity reaches 93% at the wavelength of 450 nm.

关 键 词：GAN基LED Ni/Ag反射镜电极 欧姆接触 反射率 比接触电阻率 

分 类 号：TN312.8[电子电信—物理电子学]