... (b) Close-in view at one clamped end of ... 10−40nm for the point contact and ~40−70nm for the 8µm-wide, large flat gate (opposite to the point-contact gate ... new and generic prototypes of SiC NW NEMS made from very thin SiC... more
... (b) Close-in view at one clamped end of ... 10−40nm for the point contact and ~40−70nm for the 8µm-wide, large flat gate (opposite to the point-contact gate ... new and generic prototypes of SiC NW NEMS made from very thin SiC epilayers using top-down nanomachining processes ...
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Parametric amplification in nanomechanical structures is demonstrated by modulating a purely intrinsic mechanical parameter of the system—the stress—via piezoelectric electromechanical coupling. Large resonance amplitude and quality... more
Parametric amplification in nanomechanical structures is demonstrated by modulating a purely intrinsic mechanical parameter of the system—the stress—via piezoelectric electromechanical coupling. Large resonance amplitude and quality factor enhancement due to parametric pumping are observed under both vacuum and ambient pressure conditions. Exploration of the region of parametric instability yields results that agree with parametric amplification theory.
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Resonant nanoelectromechanical systems (NEMS) are attracting interest in a broad variety of applications ranging from ultrasensitive mass and force detectors to quantum limited devices. However, an efficient, fully integrated scheme for... more
Resonant nanoelectromechanical systems (NEMS) are attracting interest in a broad variety of applications ranging from ultrasensitive mass and force detectors to quantum limited devices. However, an efficient, fully integrated scheme for actuation and detection remains a challenge. This talk reviews our recent progress in addressing this problem. First, we obtain excellent actuation efficiency using multilayered piezoelectric nanostructures. Second, we employ
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Parametric resonance and amplification are important in both fundamental physics and technological applications. Here we report very high frequency (VHF) parametric resonators and mechanical-domain amplifiers based on... more
Parametric resonance and amplification are important in both fundamental physics and technological applications. Here we report very high frequency (VHF) parametric resonators and mechanical-domain amplifiers based on nanoelectromechanical systems (NEMS). Compound mechanical nanostructures patterned by multilayer, top-down nanofabrication are read out by a novel scheme that parametrically modulates longitudinal stress in doubly clamped beam NEMS resonators. Parametric pumping and signal amplification are demonstrated for VHF resonators up to approximately 130 MHz and provide useful enhancement of both resonance signal amplitude and quality factor. We find that Joule heating and reduced thermal conductance in these nanostructures ultimately impose an upper limit to device performance. We develop a theoretical model to account for both the parametric response and nonequilibrium thermal transport in these composite nanostructures. The results closely conform to our experimental observations, elucidate the frequency and threshold-voltage scaling in parametric VHF NEMS resonators and sensors, and establish the ultimate sensitivity limits of this approach.
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Understanding and controlling nonlinear coupling between vibrational modes is critical for the development of advanced nanomechanical devices; it has important implications for applications ranging from quantitative sensing to fundamental... more
Understanding and controlling nonlinear coupling between vibrational modes is critical for the development of advanced nanomechanical devices; it has important implications for applications ranging from quantitative sensing to fundamental research. However, achieving accurate experimental characterization of nonlinearities in nanomechanical systems (NEMS) is problematic. Currently employed detection and actuation schemes themselves tend to be highly nonlinear, and this unrelated nonlinear response has been inadvertently convolved into many previous measurements. In this Letter we describe an experimental protocol and a highly linear transduction scheme, specifically designed for NEMS, that enables accurate, in situ characterization of device nonlinearities. By comparing predictions from Euler-Bernoulli theory for the intra- and intermodal nonlinearities of a doubly clamped beam, we assess the validity of our approach and find excellent agreement.
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Due to low power operation, intrinsic integrability and compatibility with CMOS processing, aluminum nitride (AlN) piezoelectric (PZE) microcantilevers are a very attractive paradigm for resonant gas sensing. In this paper, we... more
Due to low power operation, intrinsic integrability and compatibility with CMOS processing, aluminum nitride (AlN) piezoelectric (PZE) microcantilevers are a very attractive paradigm for resonant gas sensing. In this paper, we theoretically investigate their ultimate limit of detection and enunciate design rules for performance optimization. The reduction of the AlN layer thickness is found to be critical. We further report
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Figure 1 (Top) A sketch of the system, which is a pair of 6× 0. 5× 0. 2 μ m doubly clamped nanobeams with 400 nm separation. The beams were illuminated by an infrared laser focused to a spot of 10 μ m and the reflected signal was... more
Figure 1 (Top) A sketch of the system, which is a pair of 6× 0. 5× 0. 2 μ m doubly clamped nanobeams with 400 nm separation. The beams were illuminated by an infrared laser focused to a spot of 10 μ m and the reflected signal was detected.(Bottom) The effective potential for the slow coordinate q 2 of the higher-frequency nanobeam for different values of the modulation frequency ω p;| q 2| gives the scaled amplitude of the vibrations at frequency ω p/2, whereas the sign of q 2 determines their phase.
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Resonant nanoelectromechanical systems (NEMS) are attracting interest in a broad variety of applications ranging from ultrasensitive mass and force detectors to quantum limited devices. However, an efficient, fully integrated scheme for... more
Resonant nanoelectromechanical systems (NEMS) are attracting interest in a broad variety of applications ranging from ultrasensitive mass and force detectors to quantum limited devices. However, an efficient, fully integrated scheme for actuation and detection remains a challenge. This talk reviews our recent progress in addressing this problem. First, we obtain excellent actuation efficiency using multilayered piezoelectric nanostructures. Second, we employ the piezoelectric properties of these structures for parametric amplification of ...