Sensitive detection of nonlinear nanomechanical motion using capacitive signal down-mixing for resonant NEMS-based sensors

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Nanoelectromechanical systems (NEMS) are emerging as strong candidates for a host of important applications in semiconductor-based technology and fundamental science. At this level of miniaturization, the electric characterization of capacitive NEMS is a challenge. In fact, the high-frequency signals are normally cut off due to the limited bandwidth of the readout circuitry dominated by stray capacitance between the large amplifier and the high impedance tunneling junction. In order to overcome such limitations, some methods have been suggested: using several amplifier stages, inserting an LC resonator, or the scanning tunneling microscopy down-mixing readout technique. Nevertheless, these methods are efficient only at oscillations below the critical amplitude due to nonlinearities which induce noise mixing. In the present paper, a new characterization technique for resonant NEMS based on capacitive down-mixing has been developed and applied to M&NEMS accelerometers. The considered method is highly sensitive and permits a simple tuning of the signal to nonlinearity ratio.

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Journal: TechConnect Briefs
Volume: 2, Nanotechnology 2012: Electronics, Devices, Fabrication, MEMS, Fluidics and Computational (Volume 2)
Published: June 18, 2012
Pages: 223 - 226
Industry sector: Sensors, MEMS, Electronics
Topic: MEMS & NEMS Devices, Modeling & Applications
ISBN: 978-1-4665-6275-2