Self-planarizing process for the fabrication of Bi2Sr2CaCu2Ox stacks

Abstract

We developed a new fabrication process for stacked intrinsic Josephson junctions using Bi2Sr2CaCu2Ox (Bi-2212) single crystals. For the fabrication of self-planarized stacks, the Bi-2212 around the stack was changed into an insulator by dipping it in a solution of dilute hydrochloric acid. For the solution concentration <0.2%, the planarization of the stack was fully achieved. For the concentration >0.5%, however, the planarization was spoiled. The current-voltage characteristic of the stacks showed distinct resistive branches with large hysteresis at 77K. The number of intrinsic junctions in the stacks linearly decreased with decreasing the concentration of the solution in the range from 0.05% to 0.2 %. The good controllability of the number of junctions in the self-planarized stacks may be useful for electronic device applications.