  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.
