Carbon Nanotube Device Operations at Elevated Temperatures

We report on modeling studies on the effects of elevated temperatures [350K-450K] on a gate-all-around field effect transistor (GAAFET) with a single-wall semiconducting zigzag (49,0) carbon nanotube as the active channel. The basis for the study are electronic band structure calculations within a tight-binding (TB) scheme incorporated in a self-consistent ensemble Monte Carlo-electrostatic solver. Phonon dispersion includes zone-folded graphene LA and LO phonons, and the lowest radial-breathing mode (RBM) dispersion. Electronphonon scattering rates are evaluated using Fermi's Golden Rule and deformation potential approximation. Device responses are compared with standard room temperature (300K) responses. Elevated temperatures are seen to decrease the device drive current, both under steady-state and device switching conditions. This is attributed to an increase in electron-phonon scattering rates with temperature. Qualitatively, the devices are seen to work appropriately at relatively higher temperatures.