Computational analysis of the contributions to the piezoelectric coefficient e(33) in ZnO nanowires: first-principles calculations

Abstract

We investigated the piezoelectric coefficient, e(33), of ZnO nanowires, subdividing it into an ionic term, e(33)(ion), and an electronic term, e(33)(el), and calculated the effects of different diameters on its value using ab initio density functional theory calculations. The e(33)(ion) term was found to be dominant, with the innermost ( outermost) atoms in the nanowires making the largest ( smallest) contribution to the term. Moreover, the density of states ( DOS) and projected DOS data revealed that the DOS tends to increase at the valence band maximum in the case of the outermost atoms, where the O 2p and Zn 3d orbital peaks increase in magnitude, resulting in hybridization and a decrease in bond length.