Improved step edges on LaAlO3 substrates by using amorphous carbon etch masks

Abstract

We report a technique for the fabrication of sharp and straight step edges on LaAlO3 (LAO) substrates by ion milling. An electron beam lithography 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 step edge junctions fabricated at the LAO steps show promising results. An IcRn product of 1 mV was obtained at 30 K. A Fraunhofer-like magnetic field dependence of Ic was obtained up to ±2 Φ0. One weak link or possibly identical weak links in series for these step edge junctions were observed from the current-voltage (I-V) curves as well as from the magnetic field dependence of the I-V curves.