Temperature-modulated scanning tunneling spectroscopy of gold nanoparticle dropcast films

The electronic conductivity of a gold nanoparticle dropcast film was examined by temperature-modulated scanning tunneling spectroscopy (STS). The low-conductance Coulomb blockade was found to shrink with increasing temperature, which at ambient temperature (ca. 290 K) diminished completely. Concomitantly, the potential spacing between adjacent peaks observed in the Coulomb staircase features exhibited a marked increase at approximately the same temperature. Both observations suggest an enhancement of the particle film electronic conductivity with increasing temperature. Such a transition was ascribed to the combined consequence of thermal activation of interparticle charge transfer and particle coherent thermal motions.