Titanium nitride (TiN x ) films are ideal for use in superconducting microresonator detectors because: a) the critical temperature varies with composition (0 < T c < 5 K); b) the normal-state resistivity is large, ρ n ∼ 100 µΩ cm, facilitating efficient photon absorption and providing a large kinetic inductance and detector responsivity; and c) TiN films are very hard and mechanically robust. Resonators using reactively sputtered TiN films show remarkably low loss (Q i > 10 7 ) and have noise properties similar to resonators made using other materials, while the quasiparticle lifetimes are reasonably long, 10−200 µs. TiN microresonators should therefore reach sensitivities well below 10 −19 W Hz −1/2 .

Microwave kinetic inductance detectors, or MKIDs, are a type of low temperature detector that exhibit intrinsic frequency domain multiplexing at microwave frequencies. We present the first theory and measurements on a MKID based on a microstrip transmission line resonator. A complete characterization of the dielectric loss and noise properties of these resonators is performed, and agrees well with the derived theory. A competitive noise equivalent power of 5 ϫ 10 −17 W Hz −1/2 at 10 Hz has been demonstrated. The resonators exhibit the highest quality factors known in a microstrip resonator with a deposited thin film dielectric.

A reagent-based treatment method was developed for the removal of sodium dodecyl sulfate (SDS) from aqueous dispersions of single-wall carbon nanotubes (SWCNTs). Based on a survey of various reagents, organic solvents emerged as the most effective at interrupting the SDS:SWCNT interaction without producing deleterious side reactions or causing precipitation of the surfactant. Specifically, treatment with acetone or acetonitrile allows for the facile isolation of SWCNTs with near complete removal of SDS through vacuum filtration, resulting in a 100x reduction in processing time. These findings were validated via quantitative analysis using thermogravimetric analysis, Raman spectroscopy, 4-point probe electrical measurement, and X-ray photoelectron spectroscopy. Subsequent thermal oxidation further enhances the purity of the reagent treated samples and yields bulk SWCNT samples with >95% carbonaceous purity. The proposed reagent treatment method thus demonstrates potential for large volume SWCNT processing.

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Using graphene nanomechanical resonators we demonstrate the extent to which the mechanical properties of multilayer graphene films are controllable, in real time, through introduction and rearrangement of defects. We show both static and re-entrant (cyclical) changes in the tensile stress using a combination of ion implantation, chemical functionalization, and thermal treatment. While the dramatic increase in static tensile stress achievable through laser annealing can be of importance for various MEMS applications, we view the direct observation of a time-variable stress as even more significant. We find that defect-rich films exhibit a slow relaxation component of the tensile stress that remains in the resonator long after the laser exposure is finished (t ≈ 100 s ≫ t), analogous to a wind-up toy. We attribute this persistent component of the time-variable stress to a set of metastable, multivacancy structures formed during the laser anneal. Our results indicate that significant stress fields generated by multivacancies, in combination with their finite lifetime, could make them a powerful and flexible tool in nanomechanics.