Fabrications of Small and High-quality Intrinsic Josephson Junctions by Combinatorial Method of Ar-ion and Focused Ga-ion Etchings

Abstract

We present a study on the fabrication of the intrinsic Josephson junctions (IJJs), which are made of Bi2Sr2CaCu2Oy (Bi2212) single crystals, by using the focused Ga-ion etching and the Ar-ion etching. We made sure that the current-voltage (I-V) characteristics of small IJJs was never influenced by the direction of a Ga-ion beam in the focused ion beam (FIB) etchings. In addition, it was found that Ar-ion etching after FIB process is quite useful to improve the performance of the I-V curves of IJJs. By using a substrate with a small hole, we succeeded in employing the double-side Ar-ion etching after the FIB microfabrication. These results strongly support that the combinatorial method of FIB and Ar-ion etchings is very important to fabricate the small and high-quality IJJs.