Fabrication process of intrinsic Josephson junction stacks in Bi sub(2)Sr sub(2)CaCu sub(2)O sub(8+) sub(x) crystals by double-sided patterning process using dilute hydrochloric acid

We have developed a new double-sided patterning (DSP) process that employs dilute acid (pH = 1.65) to fabricate Bi sub(2)Sr sub(2)CaCu sub(2)O sub(8+) sub(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 = 77 K.