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arXiv 0904.3748cond-mat.mes-hallcond-mat.other
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DC驱动下单晶的自发机械振荡

Spontaneous mechanical oscillation of a DC driven single crystal

Kim L. Phan, Peter G. Steeneken, Martijn J. Goossens, Gerhard E. J. Koops, Greja J. A. M. Verheijden, Joost T. M. van Beek

摘要:

减小机械振荡器的尺寸具有很大的兴趣,因为这可以导致定时和频率参考设备的小型化,而且还因为小型机械振荡器作为极其敏感的传感器的潜力。在这里,我们表明,一个单晶硅谐振器结构自发地开始振荡时,由一个恒定的直流电流(DC)驱动。机械振荡是由纳米梁中的电热机械反馈效应维持的,纳米梁作为机械位移放大器操作。谐振器块的位移被放大,因为它通过压阻效应调制纳米梁中的电阻加热功率,这导致温度变化,该温度变化引起来自纳米梁的热膨胀反馈力作用在谐振器块上。这种自放大效应几乎可以发生在任何导电材料中,但当电流密度和机械应力集中在纳米尺度的梁中时特别有效。

英文摘要:

There is a large interest to decrease the size of mechanical oscillators since this can lead to miniaturization of timing and frequency referencing devices, but also because of the potential of small mechanical oscillators as extremely sensitive sensors. Here we show that a single crystal silicon resonator structure spontaneously starts to oscillate when driven by a constant direct current (DC). The mechanical oscillation is sustained by an electrothermomechanical feedback effect in a nanobeam, which operates as a mechanical displacement amplifier. The displacement of the resonator mass is amplified, because it modulates the resistive heating power in the nanobeam via the piezoresistive effect, which results in a temperature variation that causes a thermal expansion feedback-force from the nanobeam on the resonator mass. This self-amplification effect can occur in almost any conducting material, but is particularly effective when the current density and mechanical stress are concentrated in beams of nano-scale dimensions.

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