Realization and properties of YBa2Cu3O7−δ Josephson junctions by metal masked ion damage technique

Abstract

We have developed a simple process to fabricate high-TC Josephson junctions by a combination of focused ion beam milling and 100 keV H2+ ion implantation. The resistively shunted junction-like current–voltage characteristics were observed in the temperature range of 48 to 4.2 K. The devices showed clear dc and ac Josephson effects. This technique is very promising in terms of simplicity and flexibility of fabrication and has potential for high-density integration.

High quality YBa/sub 2/Cu/sub 3/O/sub 7-δ Josephson junctions and junction arrays fabricated by masked proton beam irradiation damage

“…5(a) we present the magnetic field modulation of a typical Josephson junction fabricated by proton beam irradiation at 50 K with 50 nm SrTiO buffer layer to stop Ga contamination. A familiar dependence of critical current upon magnetic field has been observed in the junction made with focused electron beam irradiation damage [3], [4], while such a modulation pattern is much poorer for the junction made with pure Au mask and 200 nm buffer [15].…”

“…We have tried deliberately leaving substantial Au mask un-cut during FIB process. This did lead to a much improved Josephson junction performance [15], [16]. Though thick Au buffer layers can be used to stop Ga contamination into YBCO, its side effects are also clear.…”

Mechanism of operation of Josephson junctions made from HTc materials by ion modification

“…In our first experiment [1][2][3][4][5] and later from others [6][7][8][9] oxygen ions were used. Other kinds of ions were also successfully used: argon [10], neon [11][12][13] and hydrogen [14,16]. Moreover, after the recent discovery of superconductivity in MgB 2 this technology was applied also to create excellent Josephson junctions from this new material [15,17,18].…”

Nano-patterning of cuprate superconductors by masked He+ ion irradiation: 3-dimensional profiles of the local critical temperature

“…Some of the previous experiments have used a variant of the stencil technique by using a pre-patterned layer of photoresist with etched voids [15,16,17,18] or a deposited metal layer that is patterned by ion beam milling [19,20] as the ion-blocking material. By irradiating YBCO with 200 keV Ne + [16] or 100 keV O + [17] ions through a 20 nm wide slit in the photoresist the fabrication of Josephson junctions has been demonstrated.…”