The electronic structures of BaBiO₃ (BBO) thin films grown on SrTiO₃ substrates are found to be thickness dependent. The origin of this behavior remains under debate and has been suggested to be attributed to the structural and compositional modifications at the BBO/SrTiO₃ interface during the first stage of film growth. Though a wetting layer with thickness of ≈1 nm has been experimentally identified at the interface, details on the microstructures of such a layer and their effect on the subsequent film growth are lacking so far, particularly at the atomic scale. Herein, atomic‐resolution scanning transmission electron microscopy is used to study the interface structure of a 30 nm‐thick BBO film grown on an Nb‐doped SrTiO₃ (STO) substrate through domain matching epitaxy. An interfacial δ‐Bi₂O₃ (BO)‐like phase with fluorite structure is identified, showing a layer‐by‐layer spacing of ≈3.2 Å along the growth direction. The orientation relationship between the BO‐like phase and surrounding perovskites (P) is found to be <001>_BO||<001>_P and <110>_BO||<100>_P. The presence of the BO‐like phase results in two types of interfaces, i.e., a coherent BO/STO and a semicoherent BBO/BO interface. Thickness variations are observed in the BO‐like layer, resulting in the formation of antiphase domains in the BBO films.

中文翻译：

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SrTiO3衬底上生长的畴匹配外延BaBiO3薄膜中的原子尺度界面结构

发现在SrTiO ₃衬底上生长的BaBiO ₃（BBO）薄膜的电子结构与厚度有关。这种行为的起源仍在争论中，并被认为是由于在膜生长的第一阶段中BBO / SrTiO ₃界面处的结构和组成的改变。尽管在界面上已通过实验确定了厚度约为≈1 nm的润湿层，但迄今为止，仍缺乏有关该层的微观结构及其对后续膜生长的影响的详细信息，特别是在原子尺度上。在这里，原子分辨率扫描透射电子显微镜用于研究在掺Nb的SrTiO ₃上生长的30 nm厚的BBO膜的界面结构。（STO）衬底通过域匹配外延。鉴定出具有萤石结构的类似δ- Bi ₂ O ₃（BO）界面相，沿生长方向层间距约≈3.2Å。发现BO型相与周围钙钛矿（P）之间的取向关系为<001> _BO || <001> _P和<110> _BO || <100> _P。类BO的存在会导致两种类型的接口，即相干的BO / STO和半相干的BBO / BO接口。在BO样层中观察到厚度变化，导致BBO膜中形成反相畴。