Full text loading...
(a) A three-dimensional schematic diagram of the micromachined quartz resonator, (b) cross-sectional view of the resonator along the dashed line shown in (a), and (c) optical picture of the fabricated quartz crystal resonator showing the etch pit and the gold electrode (Note: The optical image shows the opposite face of the resonator in comparison to the schematic illustration to highlight the etched surface.) The diameter of the etched diaphragm was 1 mm and the diameter of the electrode was . The diaphragm was etched in a 1 in AT-cut quartz disk, thick, obtained from Boston Piezo-Optics Inc. The final thickness of the diaphram realized was .
The quality factor of the resonator increases with sequential loading of SWNTs. A direct evidence for the deposition of SWNTs is indicated from the decrease in the resonance frequency as more and more SWNTs are added on the surface. When the coated resonators are subject to vacuum , the factor increases further due to desorption of physisorbed, chemisorbed, and trapped gas and solvent molecules in the SWNTs. Correspondingly, the resonance frequency increases in vacuum because of desorption of mass (gas and solvent) molecules from its surface.
The factor of the resonator coated with SWNTs increases when kept in a vacuum of over several hours. The increase follows a characteristic law indicating the desorption process of gases from the SWNTs on the surface of the resonator is probabilistic. When the vacuum is released and the resonator operated in air, some of the gases are readsorbed causing the resonator factor to decrease.
factor of the resonator as a function of the motional resistance of the resonator shows the expected dependence for both air and vacuum ambients as seen by the curve fits.
factor of the as fabricated quartz resonator and upon the deposition of SWNTs in air and vacuum ambient. For all the three resonators a improvement in the factor is observed for SWNT coated resonator in vacuum.
Article metrics loading...