Abstract
Mechanical resonators have wide applications in sensing bio- chemical substances, and provide an accurate method to measure the intrinsic elastic properties of oscillating materials. A high resonance order with high response frequency and a small resonator mass are critical for enhancing the sensitivity and precision. Here, we report on the realization and direct observation of high- order and high- frequency silicon nanowire ( Si NW) resonators. By using an oscillating electric- field for inducing a mechanical resonance of singlecrystalline Si NWs inside a transmission electron microscope ( TEM), we observed resonance up to the 5th order, for both normal and parametric modes at 100 MHz frequencies. The precision of the resonant frequency was enhanced, as the deviation reduced from 3.14% at the 1st order to 0.25% at the 5th order, correlating with the increase of energy dissipation. The elastic modulus of Si NWs was measured to be 169 GPa in the [ 110] direction, and size scaling effects were found to be absent down to the 20 nm level.