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.

Mechanical Resonances of Helically Coiled Carbon Nanowires

“…Briefly, in the HDR method, a cantilever is actuated by either static or dynamic charge induction depending on several factors such as the presence of static charges, functional groups, and intrinsic electrical conductivity of the cantilevered structure. In the absence of V dc , the dynamic (static) charge induction mechanism often resulted in a vibration at twice (same) the driving frequency for well-grounded electrically conducting cantilevers 19 . Accordingly, we observed the motion of a cantilevered HCNW ~1 Hz under the dark-field optical microscope to confirm the presence of dynamic charge induction mechanism and ensure that HCNW was properly grounded.…”

Ringdown sensing method

“…The output signal at the cantilever fundamental resonance frequency is partially or completely obscured by the parasitic signal which has the same frequency as the driving signal [2]. Detection of the signal at higher harmonics, such as in the harmonic detection of resonance method, is a simple technique to overcome this problem [2][3][4][5][6][7][8]. However, an alternate method to reduce this interference is to detect the ringdown signal in the absence of a driving signal.…”