Flexoelectricity Modulated Electron Transport of 2D Indium Oxide

Abstract

AbstractThe phenomenon of flexoelectricity, wherein mechanical deformation induces alterations in the electron configuration of metal oxides, has emerged as a promising avenue for regulating electron transport. Leveraging this mechanism, stress sensing can be optimized through precise modulation of electron transport. In this study, the electron transport in 2D ultra‐smooth In2O3 crystals is modulated via flexoelectricity. By subjecting cubic In2O3 (c‐In2O3) crystals to significant strain gradients using an atomic force microscope (AFM) tip, the crystal symmetry is broken, resulting in the separation of positive and negative charge centers. Upon applying nano‐scale stress up to 100 nN, the output voltage and power values reach their maximum, e.g. 2.2 mV and 0.2 pW, respectively. The flexoelectric coefficient and flexocoupling coefficient of c‐In2O3 are determined as ≈0.49 nC m−1 and 0.4 V, respectively. More importantly, the sensitivity of the nano‐stress sensor upon c‐In2O3 flexoelectric effect reaches 20 nN, which is four to six orders smaller than that fabricated with other low dimensional materials based on the piezoresistive, capacitive, and piezoelectric effect. Such a deformation‐induced polarization modulates the band structure of c‐In2O3, significantly reducing the Schottky barrier height (SBH), thereby regulating its electron transport. This finding highlights the potential of flexoelectricity in enabling high‐performance nano‐stress sensing through precise control of electron transport.