IMPROVED STEP EDGES ON LAALO3 SUBSTRATES BY USING AMORPHOUS-CARBON ETCH MASKS

We report a technique for the fabrication of sharp and straight step e dges on LaAlO3 (LAO) substrates by ion milling. An electron beam litho graphy defined amorphous carbon film was used as an etch mask. It had very low ion milling rate and was easily prepared and removed. Atomic force microscopy was used to determine the step profile. YBa2Cu3O7 ste p edge junctions fabricated at the LAO steps show promising results. A n I(c)R(n) product of 1 mV was obtained at 30 K. A Fraunhofer-like mag netic field dependence of I(c) was obtained up to +/-2 PHI0. One weak link or possibly identical weak links in series for these step edge ju nctions were observed from the current-voltage (I-V) curves as well as from the magnetic field dependence of the I-V curves.