Charge carrier transport through the probe-sample junction can have substantial consequences for outcomes of electrical and electromechanical atomic-force-microscopy (AFM) measurements. For understanding physical processes under the probe, we carried out conductive-AFM (C-AFM) measurements of local current-voltage (I-V) curves as well as their derivatives on samples of a mixed ionic-electronic conductor Li1-xMn2O4 and developed an analytical framework for the data analysis. The implemented approach discriminates between contributions the highly resistive sample surface layer and the bulk with the account of ion redistribution in the field of the probe. It was found that, with increasing probe voltage, the conductance mechanism in the surface layer transforms from Pool-Frenkel to space-charge-limited current. The surface layer significantly alters the ion dynamics in the sample bulk under the probe, which leads, in particular, to a decrease of the effective electromechanical AFM signal associated with the ionic motion in the sample. The framework can be applied for the analysis of electronic transport mechanisms across the probe/sample interface as well as to uncover the role of the charge transport in the electric field distribution, mechanical, and other responses in AFM measurements of a broad spectrum of conducting materials.

中文翻译：

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扫描探针显微镜中探针/离子导体界面的局部电子传输

通过探针-样品结的电荷载流子传输会对电气和机电原子力显微镜 (AFM) 测量的结果产生重大影响。为了理解探针下的物理过程，我们对混合离子电子导体 Li1-xMn2O4 的样品进行了局部电流 - 电压 (IV) 曲线及其衍生物的导电 AFM (C-AFM) 测量，并开发了一种分析数据分析框架。所实施的方法通过考虑探针场中的离子重新分布来区分高电阻样品表面层和本体的贡献。发现随着探针电压的增加，表面层的电导机制从 Pool-Frenkel 转变为空间电荷限制电流。表面层显着改变了探针下样品体中的离子动力学，这尤其会导致与样品中离子运动相关的有效机电 AFM 信号的降低。该框架可用于分析探针/样品界面上的电子传输机制，以及揭示电荷传输在广泛导电材料的 AFM 测量中的电场分布、机械和其他响应中的作用.