The research on strain in epitaxial thin films has attracted lots of attention since strain in semiconductors may significantly affect the quality of materials and the performance of devices. In this work, we focus on the strain in -GaO thin films grown by metal-organic chemical vapor deposition (MOCVD) on c-plane sapphire substrates. Combining X-ray Diffraction and wafer bowing measurements, it is confirmed that all the -GaO epi-films exhibit tensile stress in ∼1 GPa level. Vicinal surface epitaxy (VSE) is adopted in order to relax the tensile stress in -GaO thin films. As the substrate miscut angle increases from 0.2 ° to 6 °, the stress is effectively reduced from 1.29 GPa to 0.68 GPa. It is also found that the strain relaxation by VSE is accompanied by defect generation and lattice tilt in the epitaxial film. A qualitative model is proposed to explain the mechanisms of strain relaxation and defect formation in the VSE of GaO/c-sapphire structure. Therefore, the VSE could be considered as an effective strategy for strain relaxation in -GaO heteroepitaxial film.

中文翻译：

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邻位 (0001) 蓝宝石衬底上生长的 ε-Ga2O3 薄膜的应变弛豫

由于半导体中的应变可能显着影响材料的质量和器件的性能，因此外延薄膜应变的研究引起了广泛的关注。在这项工作中，我们重点研究在 c 面蓝宝石衬底上通过金属有机化学气相沉积 (MOCVD) 生长的 -GaO 薄膜中的应变。结合X射线衍射和晶圆弯曲测量，证实所有-GaO外延膜都表现出〜1 GPa水平的拉应力。采用邻位表面外延（VSE）来松弛-GaO薄膜中的拉应力。随着基板错切角从0.2°增加到6°，应力有效地从1.29 GPa降低到0.68 GPa。还发现，VSE引起的应变弛豫伴随着外延膜中缺陷的产生和晶格倾斜。提出了一个定性模型来解释 GaO/c-蓝宝石结构的 VSE 中应变弛豫和缺陷形成的机制。因此，VSE可以被认为是-GaO异质外延薄膜应变弛豫的有效策略。