Excess heat generated in integrated circuits is one of the major problems of modern electronics. Surface phonon-polariton scattering is shown here to be the dominant mechanism for hot charge carrier energy dissipation in a nanotube device fabricated on a polar substrate, such as SiO(2). By use of microscopic quantum models, the Joule losses were calculated for the various energy dissipation channels as a function of the electric field, doping, and temperature. The polariton mechanism must be taken into account to obtain an accurate estimate of the effective thermal coupling of the nonsuspended nanotube to the substrate, which was found to be 0.1-0.2 W/(m x K) even in the absence of the bare phononic thermal coupling.

Carbon nanotubes (CNTs) have large intrinsic carrier mobility due to weak acoustic phonon scattering. However, unlike two-dimensional metal-oxide-semiconductor field effect transistors (MOSFETs), substrate surface polar phonon (SPP) scattering has a dramatic effect on the CNTFET mobility, due to the reduced vertical dimensions of the latter. We find that for the van der Waals distance between CNT and an SiO2 substrate, the low-field mobility at room temperature is reduced by almost an order of magnitude depending on the tube diameter. We predict additional experimental signatures of the SPP mechanism in dependence of the mobility on density, temperature, tube diameter, and CNT-substrate separation.

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