Morphology and seebeck coefficients of electrodeposited Bi2Se3 films grown onto Au(111)/Si substrates
Morphology and seebeck coefficients of electrodeposited Bi2Se3 films grown onto Au(111)/Si substrates
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DOI：
10.1016/j.electacta.2020.137554
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发表时间：
2021-02
影响因子：
6.6
通讯作者：
R. Ahmed;Md. Golam Rosul;Yin Xu;M. Zebarjadi;G. Zangari
中科院分区：
文献类型：
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作者：
R. Ahmed;Md. Golam Rosul;Yin Xu;M. Zebarjadi;G. Zangari
Bi 2Se 3中的多晶型使其能够被调谐以获得独特的电学、热学和光学特性。通常报道的菱面体结构是拓扑绝缘体，具有0.2- 0.3eV带隙的窄禁带半导体，并且已经被广泛研究用于热电应用。另一种正交结构是具有0.9-1.2 eV的较大带隙的半导体。制造这些正交和菱形结构的混合物的机会为材料工程提供了优化其电学和热学性能的机会。在这里，我们报告的形态和塞贝克系数的混合相，富硒，n型Bi 2Se 3薄膜的电沉积制备使用酸性浴。观察到光滑膜的成核后形成之后是晶体的出现和通过新形成的晶体的聚结的继续生长。还观察到薄膜的室温塞贝克系数随薄膜厚度而变化，从-90 µV/K（0.74 µm厚度）增加到最大值-184.4 µV/K（1.84 µm厚度），并逐渐降低到-100.8 µV/K（5.72 µm厚度）。Bi 2Se 3薄膜的XRD图谱分析表明，Seebeck系数的厚度依赖性与从纯菱方相到斜方相和菱方相的混合相的转变有关。通过计算研究Bi 2Se 3晶体的带结构和纯斜方晶体和纯菱方晶体的Seebeck系数，进一步讨论了Seebeck效应的厚度依赖性.
Polymorphism in Bi2Se3allows it to be tuned for unique electrical, thermal, and optical properties. The commonly reported rhombohedral structure is a topological insulator, a narrow gap semiconductor with a bandgap of 0.2–0.3 eV, and has been widely studied for thermoelectric applications. The alternative orthorhombic structure is a semiconductor with a larger bandgap of 0.9–1.2 eV. The opportunity to fabricate a mixture of these orthorhombic and rhombohedral structures provides a chance for materials engineering to optimize its electrical and thermal properties. Here we report the morphology and the Seebeck coefficient of mixed-phase, Se-rich, n-type Bi2Se3films prepared by electrodeposition using an acidic bath. Post-nucleation formation of smooth films was observed to be followed by the emergence of crystals and continued growth through the coalescence of the newly formed crystals. The room temperature Seebeck coefficients of the films were also observed to vary as a function of the film thickness, increasing from -90 µV/K (0.74 µm thickness) to a maximum of -184.4 µV/K (1.84 µm thickness) and gradually decreasing to -100.8 µV/K (5.72 µm thickness). Analysis of XRD patterns for the Bi2Se3films showed that the thickness dependence of Seebeck coefficients was related to the transition from pure rhombohedral to a mixture of orthorhombic and rhombohedral phases. The thickness dependent Seebeck effect was further discussed by the computational study of the Bi2Se3band structures and Seebeck coefficients of pure rhombohedral and pure orthorhombic structures.