为了研究SiO2对多层结构GaN外延片的热应力的影响，以直径d为Φ40 mm的GaN外延片为研究对象，利用有限元分析法分别对蓝宝石/AlN/GaN和蓝宝石/SiO2/AlN/GaN这两种光阴极组件外延片表面热应力进行理论计算和仿真。在其他结构参数相同的情况下，分别分析了两种光阴极组件外延片径向和厚度方向的应力分布，分析了外延片热应力分布及影响因素。分析结果显示: 在1 200 ℃的生长温度下，径向区域内的热应力分布比较均匀，厚度方向的热应力均在衬底和外延层的界面上发生突变。最后分析了外延片生长温度、蓝宝石衬底和GaN、AlN过渡层厚度对表面热应力的影响。

In order to research the influence of SiO2 on thermal stress of multi-layer GaN epitaxial wafer, the surface stresses in sapphire/AlN/GaN and sapphire/SiO2/AlN/GaN epilayers with a diameter of 40 mm were respectively calculated and simulated by the finite element modeling method. The epilayer stress distribution in the radial and axial directions of two epilayers were analyzed with the same other structure parameters, and the thermal stress influence factor was analyzed. The results indicate that the epitaxial wafer thermal stress was uniformly distributed in the radial direction and there were mutations on the substrate and epitaxial layer in the axial direction at 1 200 ℃. Finally the influence of the growth temperature,the GaN and AlN transition layers thickness and the sapphire substrate thickness on surface thermal stress was analyzed.