Low temperature internal friction of diamond-like carbon films

Liu, Xiao; Photiadis, Douglas M.; Bucaro, J. A.; Vignola, Joseph F.; Houston, Brian H.; Wu, Houzheng; Chrisey, Douglas B.

doi:10.1016/j.msea.2003.08.104

Cited by 10 publications

(12 citation statements)

References 17 publications

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“…Similar processes might be expected in ta-C. In one study of internal dissipation in amorphous carbon films of varying 4-fold content, the room temperature dissipation was similar to that reported here, but a strong temperature dependence was observed in the range of 10 K to 300 K [35]. The authors attributed the dissipation to structural disorder in the films, but the nature of the defects was not identified.…”

Section: Fig 511 Plot Of the Quality Factor In Ta-c Oscillators Vesupporting

confidence: 80%

“…2 shows no change in hardness even though its Raman spectra shows evident though less graphitization. The data do not rule out a slight increase in hardness with fluence, similar to results reported for furnace annealed films [34,35]; however, the most straightforward interpretation is a constant hardness with annealing until the damage threshold is reached.…”

Section: Resultssupporting

confidence: 55%

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Nano-electromechanical oscillators (NEMOs) for RF technologies.

Wendt¹,

Czaplewski²,

Gibson

et al. 2004

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Nano-electromechanical oscillators (NEMOs), capacitively-coupled radio frequency (RF) MEMS switches incorporating dissipative dielectrics, new processing technologies for tetrahedral amorphous carbon (ta-C) films, and scientific understanding of dissipation mechanisms in small mechanical structures were developed in this project. NEMOs are defined as mechanical oscillators with critical dimensions of 50 nm or less and resonance frequencies approaching 1 GHz. Target applications for these devices include simple, inexpensive clocks in electrical circuits, passive RF electrical filters, or platforms for sensor arrays. Ta-C NEMO -3 -arrays were used to demonstrate a novel optomechanical structure that shows remarkable sensitivity to small displacements (better than 160 fm/Hz 1/2 ) and suitability as an extremely sensitive accelerometer. The RF MEMS capacitively-coupled switches used ta-C as a dissipative dielectric. The devices showed a unipolar switching response to a unipolar stimulus, indicating the absence of significant dielectric charging, which has historically been the major reliability issue with these switches. This technology is promising for the development of reliable, lowpower RF switches. An excimer laser annealing process was developed that permits full in-plane stress relaxation in ta-C films in air under ambient conditions, permitting the application of stress-reduced ta-C films in areas where low thermal budget is required, e.g. MEMS integration with pre-existing CMOS electronics. Studies of mechanical dissipation in micro-and nano-scale ta-C mechanical oscillators at room temperature revealed that mechanical losses are limited by dissipation associated with mechanical relaxation in a broad spectrum of defects with activation energies for mechanical relaxation ranging from 0.35 eV to over 0.55 eV. This work has established a foundation for the creation of devices based on nanomechanical structures, and outstanding critical research areas that need to be addressed for the successful application of these technologies have been identified.-4 - CONTENTS

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Section: Fig 511 Plot Of the Quality Factor In Ta-c Oscillators Vesupporting

confidence: 80%

Section: Resultssupporting

confidence: 55%

Nano-electromechanical oscillators (NEMOs) for RF technologies.

Wendt¹,

Czaplewski²,

Gibson

et al. 2004

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“…The smallest internal friction that we have ever observed, a-C doped with nitrogen, 14 is about one order of magnitude below the glassy range. In a-Si films, we have reached an internal friction about three orders of magnitude below the glassy range using hot-wire chemical vapor deposition that incorporates approximately 1 at.…”

Section: A Tunneling States In A-c Filmsmentioning

confidence: 68%

“…3 is the internal friction of the prototypical glass, amorphous SiO 2 ͑a-SiO 2 ͒ measured at 4500 Hz. 33 In our previous study on a-C films prepared at the Naval Research Laboratory, 14 we found that their internal friction plateaus can vary over an order of magnitude depending on laser fluences, dopings, and annealing, with the highest internal friction still below the glassy range. Our current results are consistent with those of the earlier study in the sense that the values of the internal friction plateaus below 20 K fall in the same order of magnitude and they are all below the glassy range.…”

Section: Resultsmentioning

confidence: 94%

“…[8][9][10] Following those pioneering studies, we have used a high sensitivity technique to study the low-temperature internal friction of various types of thin films of a-Si, a-Ge, and also amorphous carbon ͑a-C͒. [11][12][13][14] We have concluded that the four-fold coordinated tetrahedral bonding is indeed an important factor in reducing the number of TLS. 13 In certain hydrogenated a-Si films, the TLS can be made to disappear completely.…”

Section: Introductionmentioning

confidence: 99%

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Microstructure dependence of low-temperature elastic properties in amorphous diamondlike carbon films

et al. 2005

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We have studied the internal friction and the relative change in the speed of sound of amorphous diamondlike carbon films prepared by pulsed-laser deposition from 0.3 K to room temperature. Like most amorphous solids, the internal friction below 10 K exhibits a temperature independent plateau. The values of the internal friction plateaus, however, are slightly below the universal glassy range where the internal frictions of almost all amorphous solids lie. Similar observations have been made in our earlier studies in the thin films of amorphous silicon and amorphous germanium, and the behavior could be well accounted for by the existence of the low-energy atomic tunneling states. In this work, we have varied the concentration of sp 3 vs sp 2 carbon atoms by increasing the laser fluence from 1.5 to 30 J / cm 2 . Our results show that both the internal friction and the speed of sound have a nonmonotonic dependence on an sp 3 / sp 2 ratio with the values of the internal friction plateaus varying between 6 ϫ 10 −5 and 1.1ϫ 10 −4 . We explain our findings as a result of a possible competition between the increase of atomic bonding and the increase of internal strain in the films, both of which are important in determining the tunneling states in amorphous solids. In contrast, no significant dependence of laser fluence is found in shear moduli of the films, which vary between 220 and 254 GPa. The temperature dependence of the relative change in speed of sound, although it shows a similar nonmonotonic dependence on laser fluence as the internal friction differs from those found in thin films of amorphous silicon and amorphous germanium, which we explain as having the same origin as the anomalous behavior recently observed in the speed of sound of thin nanocrystalline diamond films.

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Nanostructure Characterization of Bismuth Telluride-Based Powders and Extruded Alloys by Various Experimental Methods

Vasilevskiy

Bourbia

Gosselin

et al. 2011

Journal of Elec Materi

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High-resolution transmission electron microscopy (HRTEM) observations of mechanically alloyed powders and bulk extruded alloys give experimental evidence of nanosized grains in bismuth telluride-based materials. In this study we combine HRTEM observations and x-ray diffraction (XRD) measurements, of both mechanically alloyed powders and extruded samples, with mechanical spectroscopy (MS) of extruded rods. Both HRTEM and XRD show that nanostructures with an average grain size near 25 nm can be achieved within 2 h of mechanical alloying from pure elements in an attritor-type milling machine. Residual strain orthogonal to the c-axis of powder nanoparticles has been evaluated at about 1.2% by XRD peak broadening. In contrast, XRD has been found unreliable for evaluation of grain size in highly textured extruded materials for which diffraction conditions are similar to those of single crystals, while MS appears promising for study of bulk extruded samples. Nanostructured extruded alloys at room temperature exhibit an internal friction (IF) background that is one order of magnitude higher than that of conventional zone-melted material with a grain size of several millimeters. IF as a function of sample temperature gives activation energies that are also different between bulk materials having nano-and millimeter-size grains, a result that is attributed to different creep mechanisms. Nanograin size, as well as orientation and volumetric proportion, provide valuable information for optimization of technological parameters of thermoelectric alloys and should be carefully cross-examined by various independent methods.

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Low temperature internal friction of diamond-like carbon films

Cited by 10 publications

References 17 publications

Nano-electromechanical oscillators (NEMOs) for RF technologies.

Nano-electromechanical oscillators (NEMOs) for RF technologies.

Microstructure dependence of low-temperature elastic properties in amorphous diamondlike carbon films

Nanostructure Characterization of Bismuth Telluride-Based Powders and Extruded Alloys by Various Experimental Methods

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