Single-electron transistor properties of Fe–SrF2 granular films

We prepared single-electron tunnelling (SET) transistors made of Fe nanodots and investigated their fundamental properties. The device films were composed of Fe nanodot arrays embedded in a SrF2 matrix fabricated by the co-evaporation method on thermally oxidized Si substrates. The Si substrates were used as backgate electrodes. The current-to-voltage curves between source and drain electrodes were nonlinear even at room temperature. Coulomb blockade was clearly observed at 8 K. Current oscillation which is another SET characteristic was confirmed in the curves of drain current versus gate voltage. The oscillation period was roughly estimated to be about 20–40 V.