Thermoelectric power of single-walled carbon nanotube films

摘要: We report measurements of the thermoelectric power (TEP) S and electrical resistance R thin films tangled ropes single-walled carbon nanotubes. Experiments at 300 K under applied force normal to plane film revealed a $\ensuremath{\sim}10--20 %$ decrease in four-probe resistance, indicating that contact between had improved. The TEP, however, was not affected by concomitant ropes. A quasilinear, diffusion TEP is observed for temperatures $T\ensuremath{\gtrsim}120 \mathrm{K},$ metallic tubes provide dominant contribution. As sample heated vacuum (degassed), with time changes sign, retaining its character. This behavior explained as consequence balance charge ${\mathrm{O}}_{2}^{\ensuremath{-}\ensuremath{\delta}}$ species which can be removed degassing an unidentified donor state. In fact, stopping process appropriate time, one achieve $S\ensuremath{\sim}0$ state over range $4 \mathrm{K}lTl500 \mathrm{K}.$ Model calculations are presented show small identified near mirror symmetry bands Fermi energy rope determined acceptor states on semiconducting tubes. broad low-$T$ feature maxima $80 \mathrm{K}lTl100 \mathrm{K}$ tentatively phonon drag.