入射角对Al_(0.5)Ga_(0.5)As-AlAs分布布拉格反射器反射光谱的影响

Research on Reflection Spectrum of Al_(0.5)Ga_(0.5)As-AlAs Distributed Bragg Reflector at Different Incidence Angles

采用传输矩阵法对Al0.5Ga0.5As-AlAs材料的发光二极管分布布拉格反射器进行入射角的反射光谱研究，计算发现反射偏振光p和s随入射角的增大呈“V”形变化，在49．8°处有最小反射值。不同入射介质[以空气和限制层（Al0.7Ga0.3）0.5In0.3P材料]下的反射光谱受入射角的影响差异很大，其中入射角对空气入射介质的反射谱影响较小，由0°入射的反射率88．13％降至45。的84．94％，反射峰值波长蓝移仅10nm；但入射角对（Al0.7Ga0.3）0.5In0.5P入射介质的反射谱影响很大，仅从0°到45°入射，反射率降幅就超过45％，反射峰值波长蓝移超过127nm。为了减缓这种影响，提出了多波长布拉格反射器结构设计。计算表明多波长分布布拉格反射器在0°～45°的入射角内比传统的分布布拉格反射器有更好的光谱特性，这对提高发光二极管的出光效率有现实意义。

The reflection spectra of Al0.5Ga0.5As-AlAs distributed Bragg reflector （DBR） at different incident angle are calculated by transfer matrix method. The reflection spectra curve of p-polarized and s-polarized plane waves vary with a‘V＇ shape with the rise of the incident angle and the lowest reflectivity is at 49.8°. The reflection spectra of different incident media [air and Al0.7Ga0.3）0.5In0.5P] are greatly different at different incident angles. The change of the reflection spectrum from air to DBR is small, the reflectivity is 88.13 % at incident angle 0° as well as 84.98% at 45°, and the peak wavelength of reflection spectrum is blue-shifted about 10 nm. But the change of reflection spectrum of from （Al0.7Ga0.3）0.5In0.5P to DBR is great, the reflectivity decreases over 45 % and the peak wavelength is blue-shifted over 127 nm from incident angle 0° to 45°. In order to reduce the changes, a new multi-wavelength DBR design is brought forward. The theoretical result shows the reflectance spectrum of multi-wavelength DBR design is better than that of the conventional DBR design, which is important to enhance light extraction from LED.