On the Performance of Carbon Nanotubes in Extreme Conditions and in the Presence of Microwaves

Report No. ARL-MR-0836
Authors: Julia B. Doggett and Ryan C. Toonen
Date/Pages: January 2013; 16 pages
Abstract: Using van der Pauw and microwave surface resistance measurements, a series of temperature-dependent data sets from carbon nanotube (CNT) thin films have been measured. The test structures were fabricated using photolithography, E-beam evaporation, and a novel CNT network deposition technique. The sheet resistance and resistivity of each sample were recorded at temperatures ranging from 0–60 °C with test currents ranging from 100 nA to 100 μA. These values demonstrated excellent linearity, with no dependence on currents. At room temperature, the sheet resistance yielded a negative temperature coefficient (of approximately –900 ppm/°C). Our objective is to analyze the effect that DC and microwave currents have on CNT thin films using a two-point measurement technique on Corbino discs and in the presence of microwaves (8–12 GHz) to determine at which temperatures a CNT thin film performs best and identify the ideal temperature range in which a CNT microchip yields the maximized sheet resistance. The results counter the trend found by the four-point measurements; a positive temperature coefficient was observed. This observation indicates the temperature coefficient of the material is actually dependent on the size of the sample tested.
Distribution: Approved for public release
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Last Update / Reviewed: January 1, 2013