Band Bending and Ratcheting Explain Triboelectricity in a Flexoelectric Contact Diode.

Olson, Karl P; Mizzi, Christopher A; Marks, Laurence D · Nano Lett · 2022

basic_science · Level V

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Abstract

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 Pt<sub>0.8</sub>Ir<sub>0.2</sub> conductive atomic force microscope probe to simultaneously deform a Nb-doped SrTiO<sub>3</sub> 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.