Self-planarizing process for the fabrication of Bi2Sr2CaCu2Ox stacks

Abstract

We developed a new fabrication process for stacked intrinsic Josephson junctions using Bi 2 Sr 2 CaCu 2 O x ( 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 77 K . 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.