Temperature-Dependent Internal Friction in Silicon Nanoelectromechanical Systems
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Temperature-Dependent Internal Friction in Silicon Nanoelectromechanical Systems Stephane Evoy1, Anatoli Olkhovets2, Dustin W. Carr3, Jeevak M. Parpia2, and Harold G. Craighead2 1
Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, VA 24061 Cornell Center for Materials Research, Cornell University, Ithaca, NY 14851 3 Bell Laboratories, Lucent Technologies, Murray Hill, NJ 07974 2
ABSTRACT The mechanical properties of micro- and nanomechanical systems are of interest from both fundamental and technological standpoints. High-frequency mechanical resonators presenting high quality factors are of interest for the development of sensitive force detecting devices, and highly efficient RF electromechanical filters and oscillators. Internal losses are the combination of both extrinsic and intrinsic issues that must be well understood for the optimization of resonator quality, and for the experimental access to fundamental nanoscopic mechanical phenomena. The temperature dependent internal friction in 1-10 MHz paddle oscillators is reported. Quality factors as high as 1000 and 2500 are observed at room temperature in metallized and non-metallized devices, respectively. Internal friction peaks are observed in all devices in the T = 160-180 K range. The position of those peaks is consistent with the Debye relaxation of previously reported surface and near-surface phenomena. INTRODUCTION Nanometer scale science and engineering is a broad and interdisciplinary area that has been growing explosively worldwide in the past few years. It has the potential of revolutionizing materials and product manufacturing, and the range and nature of functionalities that can be accessed. Microelectromechanical systems (MEMS) have already revolutionized the microelectronics industry by providing a new range of integrative functionalities to booming fields such as biotechnology, communications, and safety devices. Advances in nanomachining, actuation, and mechanical characterization have recently allowed the fabrication and operation of freestanding objects in silicon and other materials, with thicknesses and lateral dimensions down to about 20 nanometers. [1] Such reduction towards nanoelectromechanical systems (NEMS) would bestow highly fruitful new applications such as nanobiotechnology, [1] attonewton detection, [2,3] and radio frequency (rf)-range operation. [4] The development of rf-range nanomechanical resonators are particular commercial interest to wireless systems by offering an integrative alternative to surface acoustic wave (SAW) technology. [4] Issues ranging from fundamental materials science to manufacturability hinder such deployment. Energy dissipation is already known to increase with reduced dimensions, [5,6] severely limiting the quality of nanometer scale devices. Such dissipative processes must be better understood in rf-range resonators in order to deploy such devices in wireless applications that demand high spectral purity.
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Mat. Res. Soc. Symp. Proc. Vol. 657 © 2001 Materials Researc
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