Fabrication and characterisation of series YBCO step-edge Josephson junction arrays

Abstract

Fabrication and characterisation of YBCO step-edge Josephson junction arrays in a series configuration are reported. The junction arrays were fabricated using CSIRO YBCO step-edge junction technology, which, owing to the flexibility of locating the junctions anywhere on the chip, makes it very attractive for implementation of multiple HTS devices and circuits. Arrays of 50 junctions in series were fabricated, and the DC current-voltage (I-V) characterisations were studied at temperatures ranging from 15 to 77 K; temperatures were obtained via either placing the samples in the vent gas of a liquid He cryostat or use of a commercial cryocooler. Eight fabricated and tested arrays, totalling 400 junctions, showed no electrically open or shorted junctions (i.e., a 100% yield of working Josephson junctions), demonstrating good fabrication reliability. Large junction normal resistances (several hundred Ωs) were obtained from the series junction arrays, making them suitable for a range of high-frequency applications. A study of the junction critical current spread within an array, magnetic field dependence of the critical current, and microwave responses of the arrays is also described.

Preparation of novel HTS films and tunnel junctions for advanced C3I sensor applications

“…An AFM scan was not available for the trench located at y = 2.11 mm. however, is on the potential new method for creating sharp 3-D structures in YBa 2 Cu 3 O x films, in particular in aiding the formation of well defined Josephson junction geometries either as a an additional tool in the formation of grain boundary, 14 step edge, 15,16 or ion damaged formed JJs, 17,18 or as a stand alone method for producing nano-bridge JJ's. 19,20 Such an approach would necessarily require a re-oxygenation step at some point during the process.…”

A broadband detector based on series YBCO grain boundary Josephson junctions

“…But, in our case, these dimensions were chosen based on the maximum resolution of the standard technology of alignment and magnetron deposition of YBaCuO films on a bicrystal substrate [ 25 ]. This problem can be mitigated by using ion irradiation [ 4 , 18 , 26 ] or step-edge junction technology [ 19 ], which will significantly increase the receiving properties and efficiency of the JJ series at high frequencies. While the integral received power of the three-port configuration increases due to better antenna matching, each individual port in the array receives less power than in the case of a single port in the antenna.…”

“…One possible way to solve this problem is to replace a single JJ by a chain or an array of JJs combined with planar coupling structures. The task of developing and calculating such systems is quite complex and faced with obscures such as unresolved Shapiro steps [ 18 – 19 ] and parasitic resonances [ 3 ].…”

Precision Magnetometers for Aerospace Applications: A Review

“…To achieve superconductivity, the SQUID needs to be operated in a cryogenic environment; this incurs large operating costs and is usually incompatible with low SWaP applications. Interestingly, it may be possible to operate “high-temperature” SQUID magnetometers (e.g., YBa 2 Cu 3 O 7 SQUIDs [ 108 ], as commercialized by Australia’s Commonwealth Scientific and Industrial Research Organisation [ 109 ] and others) on Titan without requiring extra cryogenic apparatus because Titan’s naturally-occurring liquid methane lakes are sufficiently cold for superconductivity to be sustained (86 K) [ 110 ]. To date, SQUID magnetometers have been deployed aboard manned planes and helicopters [ 102 ] for applications such as nondestructive archaeology and geomagnetic evaluation [ 105 ]; nevertheless, their most common use in the aerospace sector is nondestructive testing for maintenance of air- and spacecraft components (e.g., [ 111 ]).…”