Position sensitive photothermoelectric effect in suspended single-walled carbon nanotube films

The photovoltage properties of suspended single-walled carbon nanotube (SWNT) films were measured in high vacuum. Experiments with localized illumination showed significant photovoltage amplitudes of up to 0.36 mV at 1.2 mW intensity. The photoresponse dependence upon the laser position was explained by a thermal mechanism that is independent of the nanotube-metal barrier. The response was also found to depend on doping heterogeneities of the film. A model was developed to deduce from the data the spatial variation of the local Seebeck coefficient for a given photovoltage profile.