Defects-enhanced flexoelectricity in nanostructures

Recent studies show that low dimensional nanostructures may exhibit nonlocal electromechanical effects such as flexoelectricity. Despite the recent progress in nanostructure growth techniques imperfections such as defects are practically unavoidable. These imperfections may enhance flexoelectric effects. Therefore, the main goal of this paper is to analyze the effects of these imperfections on linear electromechanical properties and on flexoelectricity. The constitutive relations for the adiabatically insulated reversible system are derived from the total differential of the general thermodynamic Gibbs potential. The mechanical and electrical balance equations coupled through the constitutive equations are then solved with finite element method for the defective nanostructures. We focus in our study on GaN-based nanostructures which are important in electronic and optoelectronic applications. They exhibit higher magnitudes of electric field compared to other semiconductors in similar contexts. Our results are presented for GaN quantum dots embedded in an AlN matrix.