Method for preparing high-temp. superconductive Josephson junction by using refractory micromask process

Abstract

The preparation of high-temp. superconductive Josephson junction includes the following steps: using conventional or double-crystal or step substrate, preparing CeO2 / YBCO double-layer film on the substrate by using in-site preparation process, preparing photoresist mask on the double-layer film, exposing and developing to obtain microbridge pattern, using plasma etching process to remove CeO2 film from microbridge zone to prepare CeO2 mask, using dilute phosphoric acid to corrode YBCO film of microbridge portion so as to completely remove YBCO of substrate, placing the above-mentioned material into film-forming system to grow out high-temp. superconductive film with required pattern so as to directly form Josephson junction.

Description

1. Technical field [0001] The invention relates to a method for preparing a high-temperature superconducting Josephson junction, in particular to a method for preparing a high-temperature superconducting Josephson junction by using a refractory micromask. 2. Background technology [0002] Superconducting Josephson junctions are also known as weakly connected junctions. The so-called weak connection refers to the structure in which two superconductors form a weak coupling in some way. Josephson once predicted that in the superconductor-insulator (barrier layer)-superconductor (SIS) tunnel junction structure, the superconductors on both sides are coupled to each other through the barrier layer. When the barrier layer is thin enough, a strange physical phenomenon will appear, namely the Josephson effect. . In fact, the Josephson effect not only occurs in SIS-type superconducting tunnel junctions, but can also be observed in other types of weakly connected structures. Since t...

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Problems solved by technology

However, this step has a relatively large impact on the junction parameters, and either method will reduce the performance of the junction

In chemical etching, it is often unavoidable that some phosphoric acid solution remains, especially in tiny areas such as the junction area, where phosphoric acid is not easy to remove, resulting in slow corrosion of the film by phosphoric acid, while YB 2 C 3 o 7-δ The contact of the film with water can also negatively affect the film properties, which will affect the properties of the film, such as critical temperature, critical current, etc.

In reactive ion etching, although water and acid are avoided with YB 2 C 3 o 7-δ film contact, but due to the inevitable temperature rise, when the temperature is higher than 400 degrees Celsius, YB 2 C 3 o 7-δ The film is extremely prone to oxygen loss in a non-oxygen environment, which affects superconductivity

For example, in the experiment, it was found that the Tc of the same sample before and after chemical etching decreased by at least 3K, and some superconducting films even became semiconducting due to careless operation, and lost their superconducting properties at low temperatures.

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