Interface-engineered YBCO edge junctions

We have fabricated all YBCO edge junctions which do not require the deposition of an interlayer or barrier material. Rather, through appropriate high-temperature vacuum annealing and in-situ ion plasma treatments, we have modified the junction interface in such a way as to lead to reliable weak link behavior. These devices display RSJ-type I-V characteristics with excellent magnetic field modulation. I/sub c/R/sub n/ values over the range 0.5 to 3 mV and corresponding R/sub n/A values of 6/spl times/10/sup -8/ to 1.2/spl times/10/sup -9/ /spl Omega/-cm/sup 2/ at 20 K are easily attained by varying the process, which is not possible in most high-T/sub c/ junction technologies. These junctions can also be very uniform and appear to be quite stable. We have observed an unusual response to applied microwave radiation. We have investigated the microstructure of these junctions using transmission electron microscopy (TEM). Results of these analyses lead us to believe these junctions are feasible as the basic components of a high-T/sub c/ circuit technology.