Flexoelectronics of centrosymmetric semiconductors

TL;DR: A giant flexoelectronic effect in bulk centrosymmetric semiconductors of Si, TiO 2 and Nb–SrTiO 3 with high strain sensitivity is observed, largely outperforming state-of-the-art Si-nanowire strain sensors and even piezoresistive, piezoelectric and ferroelectric nanodevices.

Abstract: Interface engineering by local polarization using piezoelectric1–4, pyroelectric5,6 and ferroelectric7–9 effects has attracted considerable attention as a promising approach for tunable electronics/optoelectronics, human–machine interfacing and artificial intelligence However, this approach has mainly been applied to non-centrosymmetric semiconductors, such as wurtzite-structured ZnO and GaN, limiting its practical applications Here we demonstrate an electronic regulation mechanism, the flexoelectronics, which is applicable to any semiconductor type, expanding flexoelectricity10–13 to conventional semiconductors such as Si, Ge and GaAs The inner-crystal polarization potential generated by the flexoelectric field serving as a ‘gate’ can be used to modulate the metal–semiconductor interface Schottky barrier and further tune charge-carrier transport We observe a giant flexoelectronic effect in bulk centrosymmetric semiconductors of Si, TiO2 and Nb–SrTiO3 with high strain sensitivity (>2,650), largely outperforming state-of-the-art Si-nanowire strain sensors and even piezoresistive, piezoelectric and ferroelectric nanodevices14 The effect can be used to mechanically switch the electronics in the nanoscale with fast response (<4 ms) and high resolution (~078 nm) This opens up the possibility of realizing strain-modulated electronics in centrosymmetric semiconductors, paving the way for local polarization field-controlled electronics and high-performance electromechanical applications Tuning a flexoelectric polarization field in centrosymmetric semiconductor single crystals enables the observation of a giant flexoelectronic effect