AlGaInN/InGaN应变补偿DBR结构设计

Design of AlGaInN/InGaN Strain-Compensation DBR Structure

设计了中心波长为520 nm的AlGaInN/InGaN应变补偿分布布拉格反射镜(DBR)结构,通过调节组分参数实现应变补偿,使DBR整体应变为0,采用传输矩阵法,计算了Al_(0.7)Ga_(0.3-x)In x N/InGaN DBR、Al_(0.8)Ga_(0.2-x)In x N/InGaN DBR、Al_(0.9)Ga_(0.1-x)In x N/InGaN DBR的反射光谱。通过对DBR结构参数进行对比,优化了其结构和反射性能。首先对比高低折射率层生长顺序,发现对于Al_(0.8)Ga_(0.14)In_(0.06)N/In_(0.123)Ga_(0.877)N DBR,先生长高折射率层时,反射率高达99.61%,而先生长低折射率层时,反射率仅为97.73%;然后对比奇数层DBR和偶数层DBR,发现两者的反射谱几乎重合,没有显著区别;通过研究DBR对数对反射率的影响,发现对数在20~30对时,反射率随着对数的增加明显上升,30~40对时反射率增长缓慢;最后研究了材料组分对反射谱的影响,发现Al组分高的DBR折射率差大,反射性能更优,而相同Al组分的AlGaInN中In含量越低反射率越高。考虑到DBR制备过程中可能出现的厚度和组分偏差,模拟了厚度和组分出现偏差时反射谱的变化,发现高低折射率层厚度每增加或减少1 nm,反射谱红移或蓝移4~5 nm;而组分的偏差使高反射带带宽和中心波长处反射率发生明显变化。本文的研究为AlGaInN/InGaN DBR的设计和制备提供了一定的理论参考。

After adjusting the component parameters of the designed AlGaInN/InGaN DBR structure with a central wavelength of 520 nm,strain compensation was realized and the overall strain of DBR turned to 0.The transmission matrix method was used to calculate the reflectance spectra of Al_(0.7)Ga_(0.3-x)In x N/InGaN DBR,Al_(0.8)Ga_(0.2-x)In x N/InGaN DBR,and Al_(0.9)Ga_(0.1-x)In x N/InGaN DBR.By comparing the structure parameters of DBR,the structure and reflection performance of DBR are optimized.First,high and low refractive index layer growth sequence was compared for Al_(0.8)Ga_(0.14)In_(0.06)N/In_(0.123)Ga_(0.877)N DBR.For DBR with first grown high refractive index layer,the reflectance is as high as 99.61%,while for DBR first grown low refractive index layer,the reflectance is only 97.73%.Then,by comparing the odd-layer DBR and even-layer DBR,it is found that the reflection spectra of the two layers are almost identical,and there is no significant difference.By comparing the periods of DBR,it is found that the reflectance increases obviously with the increase of period number between 20 and 30 pairs,while the reflectance increases slowly with the increase of period number between 30 and 40 pairs.At last,the influence of the material components on the reflection spectrum is studied.It is found that the DBR with high Al component has a large refractive index difference and better reflection performance,while the lower content of In in the same Al component AlGaInN,the higher the reflectivity.Due to the possible deviation of thickness and component in the preparation of DBR,the changes of reflection spectra resulted from the deviation of thickness and components were simulated.It is found that the reflection spectrum is red-shifted or blue-shifted by 4 nm to 5 nm when the layer thickness of high or low refractive index is increased or decreased by 1 nm.While the component deviations caused significant changes in high anti-band bandwidth and reflectivity at central wavelength.The study in this paper provides some theoretical reference for the design and preparation of AlGaInN/InGaN DBR.