Fabrication of YBCO Josephson Junction Using Wet Etching

Abstract

Nano-bridge style Josephson junctions have the possibility of creating a dense high temperature superconducting circuits. The junctions are created using to two step etch. The first, wide area etch defines the overall shape of the Josephson junction and the second etch defines a small non-superconducting barrier by thinning the material to a thickness that cannot support the superconducting state. The wide area etching of the high temperature superconductor yttrium barium copper oxide (YBCO) is very sensitive to high temperature and water, which can destroy its superconducting properties. We have explored several different methods of wet etching of YBCO and determined their effects on the superconductivity of the material. The wet etches examined are weak acid etches of nitric acid, phosphoric acid, and a bromine alcohol solution. The bromine alcohol solution prove to be the ideal etch for our purposes.