With the aim to find out the value of an electronic charge that the Fe atoms acquire when they are doped in Ge bulk, a set of experimental and density functional theory (DFT) studies have been carried out of the model systems consisting of intermixed Fe–Ge films. Such films were prepared by electron and thermal evaporation in ultra-high vacuum (UHV) on the surface of Mo(110) substrate by initial formation of the Ge film of a mean thickness of 7.5 nm, onto which the Fe films were subsequently deposited, maintaining certain Fe to Ge concentration ratio, namely, 0.2, 0.4, 0.7 and 1.0. Annealing of such double Fe–Ge films results in notable interdiffusion of the components with quite uniform distribution of the elements throughout the intermixed layer. The details of formation of such layers were in-situ controlled by Auger electron spectroscopy (AES), low-energy ion scattering spectroscopy (LEIS), low-energy electron diffraction (LEED) and work function measurements, in combination with Ar ion depth profiling. By analyzing the Fe Auger LMM-triplet, the absolute values of the charge that Fe atoms acquire when doped in Ge, were estimated for four different Fe–Ge intermixed layers with above-mentioned different Fe to Ge concentration ratio. The corresponding plot of the charge versus Fe to Ge concentration allows to estimate the charge of a single doped Fe atom, which equals to +0.34e (electron charge units) and gradually decreases to 0.07e for high Fe concentration. To verify the experimental values of the Fe charge the calculations were done by periodic DFT as implemented in full-potential FHI-aims code. Among the used algorithms of Mulliken, Hirshfeld, and Bader's atoms-in-molecules, the latter gives good correlation between charges of Fe dopant and its concentration.

为了找出 Fe 原子掺杂在 Ge 中时获得的电子电荷值，对由混合 Fe- 组成的模型系统进行了一系列实验和密度泛函理论 (DFT) 研究。葛片。这种薄膜是通过在超高真空（UHV）中电子和热蒸发在Mo（110）基底表面上制备的，首先形成平均厚度为7.5 nm的Ge薄膜，随后在其上沉积Fe薄膜，保持一定的Fe与Ge浓度比，即0.2、0.4、0.7和1.0。这种双 Fe-Ge 薄膜的退火会导致成分显着的相互扩散，并且元素在整个混合层中的分布非常均匀。这些层的形成细节由俄歇电子能谱 (AES)、低能离子散射能谱 (LEIS)、低能电子衍射 (LEED) 和功函数测量结合 Ar 离子深度分析进行原位控制。通过分析 Fe Auger LMM-三重态，对于具有上述不同 Fe 与 Ge 浓度比的四个不同 Fe-Ge 混合层，估计了 Fe 原子在 Ge 中掺杂时获得的电荷绝对值。电荷与 Fe 到 Ge 浓度的对应关系图可以估计单个掺杂 Fe 原子的电荷，该电荷等于 +0.34e（电子电荷单位），并在高 Fe 浓度时逐渐降低至 0.07e。为了验证 Fe 电荷的实验值，通过周期性DFT进行计算，如在全势 FHI-aims 代码中实现的那样。在 Mulliken、Hirshfeld 和 Bader 的分子中原子算法中，后者给出了 Fe 掺杂剂的电荷与其浓度之间良好的相关性。