The ability to reproducibly synthesize thin films with precise composition and controlled structure is essential for fundamental study and mass production. Here, we demonstrate the hybrid molecular beam epitaxy (MBE) growth of epitaxial, single crystalline BaTiO₃ films with different thicknesses on Nb-doped SrTiO₃ substrates with atomically smooth surfaces. By combining scanning transmission electron microscopy, temperature-dependent high-resolution x-ray diffraction, reflection high-energy electron diffraction, and atomic force microscopy, we study the effect of growth conditions and the interplay between stoichiometry and epitaxial strain on the resulting structure. Furthermore, we demonstrate a close to bulk-like ferroelectric phase transition in thicker films and highlight the effect of strain on the phase transition temperature. This work establishes the hybrid MBE approach for the growth of heteroepitaxial BaTiO₃ films on conducting substrates with scalable thickness and controlled stoichiometry.

中文翻译：

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BaTiO3薄膜的混合分子束外延生长

可重复合成具有精确成分和受控结构的薄膜的能力对于基础研究和大规模生产至关重要。在这里，我们展示了不同厚度的外延单晶 BaTiO ₃薄膜在 Nb 掺杂的 SrTiO ₃上的混合分子束外延 (MBE) 生长具有原子级光滑表面的基板。通过结合扫描透射电子显微镜、温度相关高分辨率 X 射线衍射、反射高能电子衍射和原子力显微镜，我们研究了生长条件的影响以及化学计量与外延应变之间的相互作用对所得结构的影响。此外，我们在较厚的薄膜中展示了接近体状的铁电相变，并强调了应变对相变温度的影响。这项工作建立了混合 MBE 方法，用于在具有可扩展厚度和受控化学计量的导电衬底上生长异质外延 BaTiO ₃薄膜。