New Double-sided Patterning Process Using a Dilute Hydrochloric Acid Solution to Fabricate Stacked Intrinsic Josephson Junctions Inside Bi2Sr2CaCu2O8+x Single Crystals

Abstract

We developed a new double-sided patterning (DSP) process using a dilute acid solution (pH=1.65) to fabricate Bi2Sr2CaCu2O8+x (Bi-2212) stacks of intrinsic Josephson junctions. The 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 photo-resist pattern was changed to a transparent material, BiOCl, which was connected with the Bi-2212 crystal. As a result, this process provides an easy way to achieve the DSP of the surface of the Bi-2212 crystal. This new DSP process allows for remarkably improved reproducibility in fabricating the Bi-2212 stacks which show good current-voltage characteristics with large hysteresis and multiple branches at T=77 K.