Surface Elastic Effects on Electromechanical Responses of a Piezoelectric Semiconducting Nanobeam

Piezoelectric semiconductors (PSCs) find extensive applications in modern smart electronic devices because of their dual properties of being piezoelectric and semiconductive. With the increasing demand for miniaturization of these devices, the performance of their components needs to be carefully designed and optimized, especially when reduced to nanosize. It has been shown that surface elastic properties play a substantial role in the mechanical performance of nanoscale materials and structures. Building on this understanding, the surface elastic effects, encompassing surface residual stress, surface membrane stiffness, and surface bending stiffness, are comprehensively taken into account to explore the electromechanical responses of a PSC nanobeam. Additionally, the flexoelectric effect on their responses is also systematically studied. The results of this work reveal that surface elastic properties predominantly influence mechanical performance, while the flexoelectric effect plays a more dominant role in electric-related quantities at the nanoscale. Notably, the significance of surface bending rigidity, which was often underestimated in the earlier literature, is demonstrated. Furthermore, owing to the flexoelectric effect, the linear distribution of electric potential and charge carriers along the length transforms into a nonlinear pattern. The distributions of electric potential and charge carriers across the cross section are also evidently impacted. Moreover, the size-dependent responses are evaluated. Our findings may provide valuable insights for optimizing electronic devices based on nanoscale PSCs.