Manipulating the Structural and Electronic Properties of Epitaxial SrCoO2.5 Thin Films by Tuning the Epitaxial Strain,ACS Applied Materials & Interfaces

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Manipulating the Structural and Electronic Properties of Epitaxial SrCoO2.5 Thin Films by Tuning the Epitaxial Strain
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2018-03-07 00:00:00 , DOI: 10.1021/acsami.8b00791
Jiali Zhao _{1,

2,

3} , Haizhong Guo _{1,

4} , Xu He ₁ , Qinghua Zhang _{1,

3} , Lin Gu _{1,

3} , Xiaolong Li ₅ , Kui-juan Jin _{1,

3} , Tieying Yang ₅ , Chen Ge ₁ , Yi Luo ₄ , Meng He ₁ , Youwen Long _{1,

3} , Jia-ou Wang ₂ , Haijie Qian ₂ , Can Wang ₁ , Huibin Lu ₁ , Guozhen Yang _{1,

3} , Kurash Ibrahim ₂

Affiliation

Structure determines material’s functionality, and strain tunes the structure. Tuning the coherent epitaxial strain by varying the thickness of the films is a precise route to manipulate the functional properties in the low-dimensional oxide materials. Here, to explore the effects of the coherent epitaxial strain on the properties of SrCoO_2.5 thin films, thickness-dependent evolutions of the structural properties and electronic structures were investigated by X-ray diffraction, Raman spectra, optical absorption spectra, scanning transmission electron microscopy (STEM), and first-principles calculations. By increasing the thickness of the SrCoO_2.5 films, the c-axis lattice constant decreases, indicating the relaxation of the coherent epitaxial strain. The energy band gap increases and the Raman spectra undergo a substantial softening with the relaxation of the coherent epitaxial strain. From the STEM results, it can be concluded that the strain causes the variation of the oxygen content in the BM-SCO2.5 films, which results in the variation of band gaps with varying the strain. First-principles calculations show that strain-induced changes in bond lengths and angles of the octahedral CoO₆ and tetrahedral CoO₄ cannot explain the variation band gap. Our findings offer an alternative strategy to manipulate structural and electronic properties by tuning the coherent epitaxial strain in transition-metal oxide thin films.

中文翻译：

通过调整外延应变来控制外延SrCoO _2.5薄膜的结构和电子性能

结构决定材料的功能，并通过应变来调整结构。通过改变膜的厚度来调整相干外延应变是控制低维氧化物材料的功能特性的精确途径。在这里，为了探索相干外延应变对SrCoO _2.5薄膜性能的影响，通过X射线衍射，拉曼光谱，光吸收光谱，扫描透射电子显微镜研究了厚度随结构变化和电子结构的变化。（STEM）和第一性原理计算。通过增加SrCoO的厚度_2.5片，Ç轴晶格常数减小，表明相干外延应变松弛。随着相干外延应变的松弛，能带隙增加并且拉曼光谱显着软化。从STEM结果可以得出结论，应变引起了BM-SCO2.5薄膜中氧含量的变化，这导致带隙随应变的变化而变化。第一性原理计算表明，应变诱导的八面体CoO ₆和四面体CoO _4的键长和键角变化无法解释带隙的变化。我们的发现为通过调节过渡金属氧化物薄膜中的相干外延应变提供了一种控制结构和电子特性的替代策略。

更新日期：2018-03-07

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