Experiment of filed-effect transistor with a channel made of NbN granular thin film

The authors describe an experimental study of the effect of an electric field on a granular superconducting thin film using a three-terminal device which has the structure of a field-effect transistor, with the channel made of NbN granular thin film. When the gate voltage is varied at low temperature, the channel resistance shows a cyclical variation of more than one cycle. The maximum resistance variation observed at 4.2 K is about 40% . The voltage period for the resistance variation seems to correspond to the induction of the electric pair charge, 2e, on a grain. It is concluded that this result is due to a new microscopic quantum effect dual to the Josephson effect and could lead to a novel three-terminal superconductor device