High temperature superconductors are eminently suitable for use in high frequency devices because of their large energy gap. We fabricated weak link Josephson junctions connected in series. The junctions were constructed of EuBa2Cu3O7-x (EBCO) superconducting thin films on bicrystal MgO substrates. We measured their microwave broadband detection (video detection) characteristics. The responsivity (Sr) of the junctions depended on the bias current and their normal state resistance. The array junctions were effective in increasing normal state resistance. We obtained a maximum Sr of 22.6 [V/W].

High-Tc superconducting flux flow transistors were fabricated with co-evaporated thin films of YBaCuO. The vortex flow channels (2 µm in width) and the device patterns were formed by Ar ion milling. The three-terminal characteristics, vortex flow characteristics, transresistance, and current gain of the device were measured. The AC input-output characteristics of the device with an Au load resistor were also measured. The measured flow voltage, transresistance and current gain are discussed in relation to these AC input-output measurements.

This letter discusses BiSrCaCuO microbridges, fabricated using an MgO-contact annealing process and nitrogen ion beam etching with a Ta/resist multilayer mask. This higher precision microbridge was confirmed to respond more sensitively to both microwave and magnetic fields by annealing at a temperature just below the melting point.