Effect of high energy electron irradiation on YBCO and application to Josephson junction fabrication

We have investigated the effects of irradiation by a focused 350 keV electron beam (e-beam) on a single crystal YBCO by means of electron energy loss spectroscopy (EELS). Electrical properties and the EELS spectra show that the damage produced by the e-beam extends well beyond the immediate region of the irradiation. Considerable information has been obtained on the nature of the damage, both chemically and structurally. The e-beam damage lends itself to a convenient method for producing Josephson junctions and we show the superior characteristics of these junctions. When combined with the focused ion beam technique, highly reproducible, low noise SQUIDs and unique planar devices can also be made.