Olson Karl P, Mizzi Christopher A, Marks Laurence D
Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60201, United States of America.
Nano Lett. 2022 May 25;22(10):3914-3921. doi: 10.1021/acs.nanolett.2c00107. Epub 2022 May 6.
Triboelectricity was recognized millennia ago, but the fundamental mechanism of charge transfer is still not understood. We have recently proposed a model where flexoelectric band bending due to local asperity contacts drives triboelectric charge transfer in non-metals. While this ab initio model is consistent with a wide range of observed phenomena, to date there have been no quantitative analyses of the proposed band bending. In this work we use a PtIr conductive atomic force microscope probe to simultaneously deform a Nb-doped SrTiO sample and collect current-bias data. The current that one expects based upon an analysis including the relevant flexoelectric band bending for a deformed semiconductor quantitively agrees with the experiments. The analysis indicates a general ratcheting mechanism for triboelectric transfer and strong experimental evidence that flexoelectric band bending is of fundamental importance for triboelectric contacts.
摩擦电现象在数千年前就已被人们认识到，但电荷转移的基本机制至今仍未被理解。我们最近提出了一个模型，其中由于局部粗糙接触导致的挠曲电能带弯曲驱动了非金属中的摩擦电荷转移。虽然这个从头算模型与广泛观察到的现象一致，但迄今为止，尚未对所提出的能带弯曲进行定量分析。在这项工作中，我们使用铂铱导电原子力显微镜探针同时对掺铌的钛酸锶样品进行变形，并收集电流-偏置数据。基于对变形半导体相关挠曲电能带弯曲的分析所预期的电流与实验结果定量相符。该分析表明了摩擦电转移的一般棘轮机制，并有强有力的实验证据表明挠曲电能带弯曲对于摩擦电接触至关重要。
