Accurate electron attenuation lengths are of critical importance in using electron spectroscopic methods to quantitatively characterize complex materials. Here, the authors show that analysis of core-level and valence-band x-ray photoelectron spectra excited with monochromatic AlKα x-rays from the substrate and measured as a function of film thickness can be used to determine electron attenuation lengths in epitaxial SrTiO₃ films on Ge(001). Closely lattice-matched epitaxial heterojunctions are ideal systems for determining attenuation lengths provided the films grow in a layer-by-layer fashion, leading to atomically flat surfaces, and the buried interfaces are atomically abrupt. In principle, either the rate of attenuation of substrate peak intensities or the rate of increase of film peak intensities can be used for this purpose. However, the authors find that structural nonuniformities in the films reduce the accuracy of electron attenuation lengths determined from photoelectrons that originate within the films. A more reliable source of information is found in photoelectrons from the substrate which traverse the film. By using the energy dependence of calculated electron attenuation lengths from the NIST database in combination with Ge 3d core and Ge-derived valence-band intensities, the authors determine electron attenuation length as a function of kinetic energy for SrTiO₃.

中文翻译：

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通过外延薄膜生长实验确定复杂材料中电子衰减长度的优势和挑战

准确的电子衰减长度对于使用电子光谱方法定量表征复杂材料至关重要。在这里，作者表明，利用从基材发出的单色AlKαx射线激发并测量为膜厚度的核能级和价带x射线光电子光谱的分析，可以用于确定外延SrTiO _3中的电子衰减长度。在Ge（001）上拍电影。紧密匹配晶格匹配的外延异质结是确定衰减长度的理想系统，只要薄膜以逐层的方式生长，导致原子表面平坦，并且掩埋的界面原子突变即可。原则上，可以将基底峰强度的衰减速率或膜峰强度的增大速率用于此目的。然而，作者发现，薄膜中的结构不均匀性降低了由源于内部的光电子确定的电子衰减长度的准确性。电影。在穿过薄膜的来自基板的光电子中发现了更可靠的信息来源。通过使用从NIST数据库计算得到的电子衰减长度的能量依赖性，结合Ge 3d核和Ge衍生的价带强度，作者确定了SrTiO _3的电子衰减长度是动能的函数。