Anisotropic-strain-relaxation-induced crosshatch morphology in epitaxial SrTiO3/NdGaO3 thin films
Anisotropic-strain-relaxation-induced crosshatch morphology in epitaxial SrTiO3/NdGaO3 thin films
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DOI：
10.1063/1.4897960
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发表时间：
2014-10
期刊：
影响因子：
1.6
通讯作者：
X. Tan;Feng Chen;Pingfan Chen;Haoran Xu;Binbin Chen;F. Jin;Guan-Yin GAO;Wenxuan Wu
中科院分区：
文献类型：
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作者：
X. Tan;Feng Chen;Pingfan Chen;Haoran Xu;Binbin Chen;F. Jin;Guan-Yin GAO;Wenxuan Wu
研究了在正交晶系NdGaO 3（NGO）的（001）O和（110）O晶面以及立方晶系（LaAlO 3）0.3（Sr 2AlTaO 6）0.7（LSAT）的（001）晶面上外延生长的SrTiO 3（STO）薄膜的应变弛豫和表面形貌。虽然平均晶格失配相似，但在STO/NGO（001）O[（110）O]薄膜上可以发现非常规则的交叉阴影表面图案，与STO/LSAT（001）的均匀表面相反。基于取向和厚度依赖的图案和高分辨率X射线衍射，我们归因于交叉阴影线形态的各向异性应变弛豫与可能的60°失配位错的形成和横向表面台阶流在STO/NGO薄膜，而各向同性应变弛豫在STO/LSAT。此外，我们表明，交叉线STO/NGO（110）O表面可以作为一个模板，以修改外延La0.6Ca0.4MnO3薄膜的磁输运性能。这项研究突出了对称性失配在确定钙钛矿氧化物薄膜的表面形态中的关键作用，除了它们的外延应变状态，并提供了一个不同的路线设计和制造功能钙钛矿氧化物器件。
We investigate the strain relaxation and surface morphology of epitaxial SrTiO3 (STO) films grown on (001)O and (110)O planes of orthorhombic NdGaO3 (NGO), and (001) plane of cubic (LaAlO3)0.3(Sr2AlTaO6)0.7 (LSAT) substrates. Although the average lattice mismatches are similar, strikingly regular crosshatched surface patterns can be found on STO/NGO(001)O[(110)O] films, contrary to the uniform surface of STO/LSAT(001). Based on the orientation and thickness dependent patterns and high-resolution x-ray diffractions, we ascribe the crosshatch morphology to the anisotropic strain relaxation with possibly the 60° misfit dislocation formation and lateral surface step flow in STO/NGO films, while an isotropic strain relaxation in STO/LSAT. Further, we show that the crosshatched STO/NGO(110)O surface could be utilized as a template to modify the magnetotransport properties of epitaxial La0.6Ca0.4MnO3 films. This study highlights the crucial role of symmetry mismatch in determining the surface morphology of the perovskite oxide films, in addition to their epitaxial strain states, and offers a different route for designing and fabricating functional perovskite-oxide devices.