Fabrication process of intrinsic Josephson junction stacks in Bi2Sr2CaCu2O8+x crystals by double-sided patterning process using dilute hydrochloric acid

Abstract

We have developed a new double-sided patterning (DSP) process that employs dilute acid (pH=1.65) to fabricate Bi2Sr2CaCu2O8+x (Bi-2212) stacks of intrinsic Josephson junctions. These stacks, which were fabricated from a single crystal of Bi-2212, were surrounded by an acid-treated product. The critical aspect of this process is that the Bi-2212 surrounding the photoresist pattern was converted into a transparent material, BiOCl, which was connected with the Bi-2212 crystal. Consequently, this process provides a simple way to achieve DSP of the surfaces of Bi-2212 crystals. This new DSP process realizes a remarkably improved reproducibility in fabricating Bi-2212 stacks that exhibit good current–voltage characteristics with a large hysteresis and multiple branches at T=77K.