Verbridge Scott S, Shapiro Daniel Finkelstein, Craighead Harold G, Parpia Jeevak M
Department of Physics and the Cornell Center for Materials Research, Cornell University, Ithaca, New York 14853, USA.
Nano Lett. 2007 Jun;7(6):1728-35. doi: 10.1021/nl070716t. Epub 2007 May 11.
We have employed a chip-bending method to exert continuous and reversible control over the tensile stress in doubly clamped nanomechanical beam resonators. Tensile stress is shown to increase the quality factor of both silicon nitride and single-crystal silicon resonators, implying that added tension can be used as a general, material-independent route to increased quality factor. With this direct stretching technique, we demonstrate beam resonators with unprecedented tunability of both frequency and quality factor. Devices can be tuned back and forth between a high and low stress state, with frequency tunability as large as several hundred percent demonstrated. Over this wide range of frequency, quality factor is also tuned by as much as several hundred percent, providing insights into the loss mechanisms in these materials and this class of nanoresonator. Devices with frequencies in the 1-100 MHz range are studied, with quality factor as high as 390,000 achieved at room temperature, for a silicon nitride device with cross-sectional dimensions below 1 microm, operating in a high stress state. This direct stretching technique may prove useful for the identification of loss mechanisms that contribute to the energy balance in nanomechanical resonators, allowing for the development of new designs that would display higher quality factors. Such devices would have the ability to resolve smaller addendum masses and thus allow more sensitive detection and offer the potential for providing access to previously inaccessible dissipation regimes at low temperatures. This technique provides the ability to dramatically tune both frequency and quality factor, enabling future mechanical resonators to be used as variable frequency references as well as variable band-pass filters in signal-processing applications.
我们采用了一种芯片弯曲方法，对双端夹紧的纳米机械梁谐振器中的拉应力进行连续且可逆的控制。结果表明，拉应力可提高氮化硅和单晶硅谐振器的品质因数，这意味着施加的张力可作为一种通用的、与材料无关的提高品质因数的途径。通过这种直接拉伸技术，我们展示了频率和品质因数具有前所未有的可调性的梁谐振器。器件可在高应力状态和低应力状态之间来回调谐，已证明频率可调性高达百分之几百。在如此宽的频率范围内，品质因数也可调高达百分之几百，这为深入了解这些材料以及这类纳米谐振器中的损耗机制提供了线索。研究了频率在1 - 100 MHz范围内的器件，对于横截面尺寸小于1微米、处于高应力状态下工作的氮化硅器件，在室温下实现了高达390,000的品质因数。这种直接拉伸技术可能有助于识别对纳米机械谐振器中的能量平衡有贡献的损耗机制，从而开发出具有更高品质因数的新设计。此类器件将有能力分辨更小的附加质量，进而实现更灵敏的检测，并有可能在低温下提供进入以前无法达到的耗散区域的途径。该技术能够显著地同时调谐频率和品质因数，使未来的机械谐振器能够用作信号处理应用中的可变频率参考以及可变带通滤波器。
