Optical controllability of single-electron tunnelling through a molecular Coulomb island in a MOS structure

摘要

The optical controllability of single-electron tunnelling using an organic molecular Coulomb island consisting of a porphyrin derivative was examined. A double-barrier tunnelling junction (DBTJ) consisting of a Si/SiO_2/molecule/SiO_2/Au multilayer exhibited the current-voltage (I-V) characteristics of a Coulomb staircase. Light irradiation was found to induce a reversible change in the threshold voltage of the Coulomb blockade. That is, optical switching of the tunnelling current was achieved under a certain bias voltage. It is believed that the light-induced switching behaviour was due to a change in the charge distribution in the areas near the molecular Coulomb islands. These results demonstrate a potential use for organic molecules in optically functional single-electron devices.