SUPERCONDUCTOR-NORMAL-SUPERCONDUCTOR BEHAVIOR OF JOSEPHSON-JUNCTIONS SCRIBED IN Y1BA2CU3O7-DELTA BY A HIGH-BRIGHTNESS ELECTRON SOURCE

We report a substantial improvement in the behavior of Josephson junct ions scribed in Y1Ba2Cu3O7-delta films using a high-brightness field-e mission electron gun source instead of a lower-brightness thermionic s ource. These junctions exhibit resistively shunted junction behavior o ver the entire temperature range from the coupling temperature to at l east 4 K, a temperature window which can be larger than 55 K. Supercon ductor-normal-superconductor character is indicated by the exponential dependence of the critical current on temperature for all temperature s below 90 K. The data demonstrate that electron irradiation under the se conditions produces a modified region which is completely normal ab ove 4 K and is narrower in width than previously obtained. (C) 1996 Am erican Institute of Physics.