Temperature effects on conduction through a molecular junction

The measured effect of temperature on charge transport through individual chemisorbed 1-nitro-2,5-di(phenylethynyl-4-mercapto)benzene molecules spanning a gold electrode gap is reported for the range of 10-300 K. Conduction is dominated by coherent superexchange at low temperatures and shifts to an incoherent hopping process above bias-dependent temperature thresholds. The results are consistent with proposed theoretical mechanisms in which bias-dependent heat dissipation from inelastic vibrational scattering within the molecule raises the temperature of the junction above that of the surrounding system, which in turn leads to the shift in the prevailing conduction process with increasing bias.