Pressure effects on the dissipative behavior of nanocrystalline diamond microelectromechanical resonators
Pressure effects on the dissipative behavior of nanocrystalline diamond microelectromechanical resonators
复制标题
压力对纳米晶金刚石微机电谐振器耗散行为的影响
DOI：
10.1088/0960-1317/25/2/025019
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发表时间：
2015
影响因子：
2.3
通讯作者：
J. Conde
中科院分区：
文献类型：
--
作者：
J. T. Santos;T. Holz;A. Fernandes;F. Costa;V. Chu;J. Conde
由于金刚石结构层的化学惰性以及高杨氏模数、高耐磨性、低热膨胀系数和非常高的导热系数，金刚石基微机电谐振器具有增强性能的潜力。本文研究了基于纳米金刚石薄膜的MEMS谐振器在不同气压下的谐振频率和品质因数。50-300 μm长的线性电桥和双端音叉的动态特性被描述为从高真空(~10 )到大气条件的测量压力的函数，其谐振频率在0.5~15 MHz之间，品质因数高达50 mTorr。真空中的共振频率和品质因数与锚固和热弹性耗散(TED)等理论模型吻合较好。由实验数据推算出纳米金刚石膜的杨氏模数在840-920 Gpa之间。由于空气中的耗散，品质因数开始下降的临界压力值取决于谐振器的长度。较长的结构具有较低的临界压力，其品质因数受TED和较低的共振频率的限制，从本征耗散到分子耗散区域，最后到粘性耗散区域，其临界压力在1-10 托的数量级。较短的谐振器具有较高的共振频率和受锚杆损耗限制的品质因数，具有较高的临界压力，有些高于大气压力，并从固有区域直接进入粘性耗散区域。
Diamond-based microelectromechanical resonators have the potential of enhanced performance due to the chemical inertness of the diamond structural layer and its high Young’s modulus, high wear resistance, low thermal expansion coefficient, and very high thermal conductivity. In this work, the resonance frequency and quality factor of MEMS resonators based on nanocrystalline diamond films are characterized under different air pressures. The dynamic behavior of 50–300 μm long linear bridges and double ended tuning forks, with resonance frequencies between 0.5 and 15 MHz and quality factors as high as 50 000 are described as a function of measurement pressure from high vacuum(~10 mTorr) up to atmospheric conditions. The resonance frequencies and quality factors in vacuum show good agreement with the theoretical models including anchor and thermoelastic dissipation (TED). The Young’s moduli for nanocrystalline diamond films extrapolated from experimental data are between 840–920 GPa. The critical pressure values, at which the quality factor starts decreasing due to dissipation in air, are dependent on the resonator length. Longer structures, with quality factors limited by TED and lower resonance frequencies, have low critical pressures, of the order of 1–10 Torr and go from an intrinsic dissipation, to a molecular dissipation regime and finally to a region of viscous dissipation. Shorter resonators, with higher resonance frequencies and quality factors limited by anchor losses, have higher critical pressures, some higher than atmospheric pressure, and enter directly into the viscous dissipation regime from the intrinsic region.