Quasi-particle injection devices for interfaces between superconductors and semiconductors

We have fabricated an injection type 3-terminal device for interface betwee n superconductor and semiconductor circuits using a high temperature superc onductor. When quasi-particles are injected from the Au electrode to a YBa2 Cu3O7-x (YBCO) bridge, superconductivity of the bridge area is weakened and I-c of the bridge decreases. Therefore, we can easily make the bridge in r esistive state by injecting sufficient amount of current I-inj. The length, width, and thickness of the bridge are 20 mum, 10 mum, and 100 nm, respect ively. The Au-YBCO contact area is 200 mum(2). When the bridge became resis tive, the resistance was about 100 Omega. The current gain \ DeltaI(c) / De ltaI(inj)\ was as high as g. However, the contact resistance was about 17 O mega, which is 200 times as large as the required value for the operation a s an interface device. This shortcoming might be overcome by appropriate an nealing.