Semimetal-barrier quasi-planar Josephson junction

Niobium-based bismuth-barrier Josephson junctions have been made whose geometrical structure is almost planar. The amplitudes of their zero-voltage currents and microwave-induced constant-voltage current-steps are periodically modulated by applied microwave radiation. Voltage current curves of the junctions have similar energy gap structures to those of point contact Josephson junctions. The value of the parameter S, defined as the ratio of the differential resistance just above the gap to that just below the gap, is about 2.0. The junctions have a barrier length of less than 100 nm, a very low capacitance and a life of several months even at room temperature. A quasi-planar Josephson junction has been turned out a hybrid of other kinds of Josephson junctions.