Preserving the Q-Factors of ZnO Nanoresonators via Polar Surface Reconstruction

TL;DR

This study uses molecular dynamics simulations to show that free polar surfaces in ZnO nanowires significantly enhance their Q-factors by inducing shell-like reconstruction that suppresses twisting motions.

Contribution

It reveals that free polar (0001) surfaces in ZnO nanoresonators lead to higher Q-factors through surface reconstruction, a novel insight into surface effects on nanomechanical resonators.

Findings

Free polar surfaces increase Q-factors by an order of magnitude.

Shell-like reconstruction suppresses twisting motions.

Higher Q-factors result from minimized mode mixing.

Abstract

We perform molecular dynamics simulations to investigate the effect of polar surfaces on the quality (Q)-factors of zinc oxide (ZnO) nanowire-based nanoresonators. We find that the Q-factors in ZnO nanoresonators with free polar (0001) surfaces is about one order of magnitude higher than in nanoresonators that have been stabilized with reduced charges on the polar (0001) surfaces. From normal mode analysis, we show that the higher Q-factor is due to a shell-like reconstruction that occurs for the free polar surfaces. This shell-like reconstruction suppresses twisting motion in the nanowires such that the mixing of other modes with the resonant mode of oscillation is minimized, and leads to substantially higher Q-factors in the ZnO nanoresonators with free polar surfaces.