Fundamental mechanism for electrically actuated mechanical resonances in ZnO nanowhiskers

Abstract

In this study, we elucidate the fundamental mechanism for electrically actuated mechanical resonances in semiconducting ZnO nanowhiskers (NWs). Based on visual detection and measurement of mechanical resonances in ZnO NWs using a scanning electron microscope (SEM), previous studies have attributed dynamic charge induction as the fundamental mechanism for the observed resonances. We show that the use of an electron beam as a resonance detection tool alters the intrinsic electrical character of the ZnO, and makes it difficult to identify the source of the charge necessary for the electrostatic actuation. A systematic study of the amplitude of electrically actuated as-grown and gold-coated ZnO NWs in the presence (absence) of an electron beam using a SEM (dark-field optical microscope) suggest that our ZnO NWs intrinsically support static charge actuation.