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Due to the roughness in the surface of the crystal sample, it is hard to use photolithography in the patterning process of the Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+/spl delta// intrinsic Josephson junction. In this paper, we report a simple technique for fabricating the Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+/spl delta// intrinsic Josephson junctions. In the patterning process, metal masks are used instead of photolithography and argon ion milling is applied to form a small mesa on the Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+/spl delta// crystal surface. Real four-probe transport measurements are made on the Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+/spl delta// intrinsic junctions and typical current-voltage characteristics with multi-branch structure have been observed, from which the superconducting gap parameter can be extracted. Additionally, from the strung hysteresis in the I-V characteristics, the capacitance C/sub J/ of the unit intrinsic Josephson junction can be estimated, which is in good agreement with that evaluated from the geometric parameters of the unit junction between the two copper oxide lagers.
Date of Publication: June 1999