2008 NSTI Nanotechnology Conference and Trade Show - Nanotech 2008 - 11th Annual

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TechConnect Summit
Clean Technology 2008

Optical Measurement of Heat Generation and Thermal Transport in Suspended Carbon Nanotubes

S.B. Cronin, A.W. Bushmaker, I-K Hsu, V.V. Deshpande, M.T. Pettes, T. Brintlinger, M.W. Bockrath, L. Shi
University of Southern California, US

Keywords:
carbon, nanotube, Raman, Ballistic, thermal, diffusive, negative differential conductance

Abstract:
We use Raman spectroscopy of to investigate the exceptional thermal and electrical properties of individual carbon nanotubes. By measuring the Raman spectra of nanotubes at extremely high current densities (510^8A/cm^2), a detailed picture of the electron-phonon scattering mechanism is revealed. Under high electrical bias, ballistic electrons emit and absorb optical phonons, significantly affecting the electrical conductance of the nanotube and resulting in the observed negative differential conductance (NDC). Thermal transport in these suspended carbon nanotubes are studied by measuring the local temperature profile T(x) along the suspended carbon nanotubes after converting the shifts in the G-band Raman mode to temperature. These profiles reveal the ratio of the thermal contact resistance to the intrinsic resistance of the nanotube itself, which is found to vary by almost four orders of magnitude among different samples. By performing spatial-dependent measurements, we are able to eliminate the effect of thermal contact resistance inherent to nanoscale systems. A theoretical analysis, including both Fourier and Landauer transport models, is used to explain the observed data. Together, these sophisticated experiments and theoretical analysis provide a more complete understanding of the exceptional thermal and electrical properties of carbon nanotubes.


Nanotech 2008 Conference Program Abstract