Electronic, Mechanical, and Piezoelectric Properties of ZnO Nanowires

TL;DR

This study uses density functional calculations to explore the electronic, mechanical, and piezoelectric properties of ZnO nanowires, revealing size-dependent behaviors and enhanced piezoelectric effects compared to bulk ZnO.

Contribution

It provides new insights into how nanowire size influences their properties, especially the piezoelectric constant, which is larger than in bulk ZnO due to free boundary effects.

Findings

Nanowire band gap and Young's modulus increase as radius decreases.

Effective piezoelectric constant in nanowires exceeds that of bulk ZnO.

Size-dependent non-monotonic variation of piezoelectric constant due to competing effects.

Abstract

Hexagonal [0001] nonpassivated ZnO nanowires are studied with density functional calculations. The band gap and Young's modulus in nanowires which are larger than those in bulk ZnO increase along with the decrease of the radius of nanowires. We find ZnO nanowires have larger effective piezoelectric constant than bulk ZnO due to their free boundary. In addition, the effective piezoelectric constant in small ZnO nanowires doesn't depend monotonously on the radius due to two competitive effects: elongation of the nanowires and increase of the ratio of surface atoms.