Three-dimensional arrays of BiSrCaCuO-2212 intrinsic Josephson junctions and zero-crossing Shapiro steps at 760 GHz

On a slice of 200–300-nm-thick Bi2Sr2CaCu2O8+x, stacks of intrinsic Josephson junctions are patterned, connected to each other, and integrated with a bow-tie antenna and some chokes. Over an area of 150 μm by 170 μm, we have been able to fabricate up to 256 stacks with over 11 000 junctions. Such three-dimensional arrays of intrinsic Josephson junctions respond sensitively to irradiation at 760 GHz from a far-infrared laser, showing clear zero-crossing Shapiro steps up to 0.75 V. In addition, possible applications in quantum voltage standards are discussed here. The high density of integration of the Josephson junctions is also promising for many other applications.