We present results of room temperature studies of the electrical characteristics of back-gated ultrathin graphite films
prepared by mechanical transfer of thin sections of Highly Oriented Pyrolytic Graphite (HOPG) to a Si/SiO2
substrate. The films studied were quite thin, exhibiting only a few graphene layers (n). Films with thickness in the
range 1 < n < 20 were studied, where n has been deduced by Atomic Force Microscopy (AFM) z-scans. The n value
deduced by AFM z-scan data was correlated with the n value deduced by Raman scattering data. We discuss at some
length, the issue of whether or not Raman scattering can provide a standalone measure of n. Electrical contacts were
made to a few of the low n (n = 1,2,3) graphene films. Most graphene films exhibited a nearly symmetric resistance
(R) anomaly vs. gate voltage (VG) in the range 25 < VG < 110 V; some films exhibited as much as a factor of ~50
decrease in R (relative to the maximum R) with changing VG. An interesting low bias shoulder on the negative side
of the resistance peak anomaly was also observed. The devices were fabricated with a lithography free process.
It has been shown that the addition of single walled carbon anotubes (SWNTs) cause an increase in the resonance frequency of micromachined clamped-clamped structures. This is believed to be due to an increase in the effective stiffness of the micromachined structures due to the high Young's modulus of carbon nanotubes. These results were obtained in spite of a relatively poor control over the orientation and aerial density of the deposited SWNTs. Finite element simulations showed an increase in the resonance frequency of up to ~25% for the simulated devices. This increase in the resonance frequency of the bridges can be attributed to the high Young's modulus (~1TPa) of the carbon nanotubes.
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