Preparation method of NbN thin film, SQUID device and preparation method of SQUID device

Abstract

The invention provides a preparation method of a NbN thin film, a SQUID device and a preparation method of the SQUID device. The preparation method of the NbN thin film comprises the following steps: performing epitaxial growth of a three-layer film structure comprising a first NbN material layer, a first insulating material layer, a second NbN material layer in sequence on a substrate in a way of magnetron sputtering; etching to form a bottom electrode pattern; forming a Josephson junction; depositing a second insulating material layer; preparing a bypass resistor; depositing a third NbN material layer and forming a top electrode. The SQUID device comprises a substrate, a superconducting ring prepared on the substrate and a Josephson junction prepared on the substrate and embedded in the loop of the superconducting ring, wherein the Josephson junction comprises a bottom electrode, an insulating material layer and a counter electrode. The invention provides a preparation method of a NbN thin film; further, a NbN/ AlN/NbN Josephson junction based SQUID device can be prepared on the basis of the preparation method, so that the SQUID device can work at a temperature higher than 4.2K; therefore, the refrigerating cost of a superconducting AQUID device is lowered.

Description

technical field [0001] The invention relates to the field of superconducting quantum interference devices, in particular to a method for preparing a niobium nitride thin film, a SQUID device and a method for preparing the same. Background technique [0002] Inserting two Josephson structures into a superconducting ring forms a superconducting quantum interference device (SuperconductingQuantumInterferenceDevice, SQUID), such as figure 1 As shown, it is a superconducting quantum device based on the Josephson effect and the principle of magnetic flux quantization. The superconducting critical current of the SQUID device changes periodically with the magnetic flux induced by the SQUID device. When the bias current of the SQUID device is greater than the maximum critical current of the device, a voltage is generated at both ends of the SQUID device, and the voltage value also varies with the SQUID device. The magnetic flux induced by the SQUID device presents periodic changes. ...

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Problems solved by technology

[0005] In view of the above-mentioned shortcoming of the prior art, the purpose of the present invention is to provide a kind of preparation method of niobium nitride thin film, SQUID device and preparation method thereof, be used to solve the low working temperature of SQUID device in the prior art, thus in economical and technical aspects limit the practical application of low-temperature SQUID devices

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