对蓝宝石-氮化镓异质膜系统的界面应力进行有限元模拟分析,研究了从生长温度(1373 K)降到室温(300 K)的过程中系统界面应力的分布情况及其影响因素,并通过理论计算验证了所建模型的合理性。模拟结果显示:系统界面应力沿径向分布均匀,只有在边缘处界面应力急剧增大。当不考虑边缘效应,分别改变氮化镓膜或蓝宝石衬底厚度,保持另一厚度不变时,薄膜系统界面应力极大值出现在蓝宝石衬底与氮化镓膜厚度之比ds/df≈1.5处,极小值出现在ds/df≈4.3处,说明薄膜系统界面应力大小不仅仅取决于热膨胀系数的差异或温差,受膜厚比的影响也很大。模拟还发现,由于晶格失配产生的应力远远大于因热失配产生的应力。

The interfacial stress in sapphire-GaN heterogeneous film system is simulated using the finite element method herein. The distribution of the interfacial stress and its influencing factors in the process of the growth temperature (1373 K) falling to the room temperature (300 K) are studied. The rationality of the proposed model was verified through theoretical calculations. Results show that the interfacial stress in the system is uniformly distributed along the radial direction, and only the interfacial stress at the edge changes suddenly and drastically. When the thickness of GaN film or sapphire substrate is changed without considering the edge effect while the thickness of another is unchanged, the maximum value of interfacial stress appears when the thickness ratio d_s/d_f of sapphire substrate to GaN film is approximately 1.5, and the minimum value appears when the thickness ratio is approximately 4.3. It shows that the interfacial stress of the film system is not determined by the difference of coefficient of thermal expansion or the difference of temperature, but it is greatly influenced by the thickness ratio. Furthermore, it is found that the stress due to lattice mismatch is much greater than that owing to thermal mismatch.