DIRECT-INJECTION HIGH-T-C DC-SQUID WITH AN UPPER YBA2CU3O7-X GROUND PLANE

We have fabricated direct-injection high-T-c superconducting quantum i nterference devices (SQUIDs) with integrated YBa2Cu3O7-x (YBCO) ground planes in the upper pan of structure, The YBCO/PrBa2Cu3O7-x(PBCO)/YBC O edge junctions with 10-nm-thick PBCO barriers showed RSJ-like curren t-voltage (I-V) characteristics before and after the ground plane form ation. We measured the voltage modulations of these SQUIDs with two di fferent hole sizes to evaluate the line inductance. At a temperature o f 30 K, the estimated line inductance under the ground plane was about 1.0 pH/square, while the estimated line inductance without the ground plane was 2.8 pH/square. (C) 1997 American Institute of Physics.