In order to research the surface thermal stress in sapphire/ZnO/GaN epilayer and the stress influence factor,the surface stress of materials with diameter of 40 mm was respectively calculated and studied by the finite element modeling method,and the rationality of the model was proved.The epilayer stress in the radial and axial direction was analyzed.The results indicated that the epilayer stress was uniform in the radial direction and there were mutations on the boundaries in the axial direction under the the temperature of 1 200 ℃;The epilayer surface thermal stress was in direct proportion to growth temperature during the temperature from 400 ℃ to 1 200 ℃.In the range of 2～2.5 mm,the thermal stress of the epitaxial layer is small.The thickness of GaN has more influence on the thermal stress in epilayer than the thickness of Sapphire substrate and ZnO transition.The results are helpful in study of new technology of epitayers growth and establishing the quality choice standard of low stress epilayer.%为了研究蓝宝石/ZnO/GaN外延片表面层热应力分布及影响因素,利用有限元分析法对直径为Φ40 mm的外延片表面热应力分布进行了理论计算和仿真,验证了仿真模型的合理性.分析了其生长温度、蓝宝石衬底和ZnO过渡层厚度对表面层热应力的影响.结果表明:在1 200℃生长温度下,外延片在径向区域内的热应力分布比较均匀;在400～1 200℃温度范围内,外延层表面应力与生长温度呈近似正比关系;衬底厚度为2～2.5 mm的范围内,外延层热应力较小.正交试验分析数据表明GaN厚度对GaN外延片的表面热应力有显著影响.该研究成果可为该类外延片生长工艺研究和低应力外延片的筛选标准制定提供借鉴.
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