Superconducting device and method of manufacturing the same
The present invention provides a superconducting device including a substrate, a first superconducting pattern formed on the substrate, an insulating pattern formed on the first superconducting pattern, and a second superconducting pattern formed at the uppermost level in the multilayered superconducting pattern. A barrier layer of a Josephson junction is formed on the lower side of, or within the second superconducting pattern. The second superconducting pattern constitutes a circuit element on the insulating pattern.
1. A superconducting device of a multilayer structure in which a first to an (n−1)th oxide superconducting layers (n is an integer more than one) and a first to an (n−1)th oxide insulating layers are alternately superposed on each other on an insulating substrate, and in which an n-th oxide superconducting layer is superposed on the (n−1)th oxide insulating layer as an uppermost-level oxide insulating layer, and which includes a Josephson junction, wherein
(i) the Josephson junction is formed by forming at least one of junction electrodes concurrently with the time when the n-th oxide superconducting layer as an uppermost-level oxide superconducting layer is superposed,
(ii) at least the uppermost-level oxide superconducting layer of the multilayer structure includes a circuit element pattern,
(iii) the uppermost-level oxide superconducting layer, and the first to the (n−1)th oxide superconducting layers as other oxide superconducting layers of the multilayer structure are made of an identical material, and
(iv) edges of the other oxide superconducting layers and the first to the (n−1)th oxide insulating layers are a tapered surface reaching the insulating substrate, and the uppermost-level oxide superconducting layer is in direct contact with the tapered surface the other oxide superconducting layers and the first to the (n−1)th oxide insulating layers, and with an upper surface of the insulating substrate.
2. The superconducting device according to claim 1 , wherein
the insulating substrate is a bicrystal substrate, and
the Josephson junction is a bicrystal-type Josephson junction formed on the substrate.
3. The superconducting device according to claim 1 or claim 2 , wherein the circuit element is any one of a wiring and a coil.
4. The superconducting device according to claim 1 , wherein
the insulating substrate is a substrate having a step on a surface thereof, and
the Josephson junction is a step-edge type Josephson junction formed on the step of the substrate.
5. A superconducting device of a multilayer structure in which a first oxide superconducting layer, an oxide insulating layer and a second oxide superconducting layer are superposed in this order on an insulating substrate, and which includes a Josephson junction, wherein
(i) the Josephson junction is formed by forming at least one of junction electrodes concurrently with the time when the second oxide superconducting layer as an uppermost-level oxide superconducting layer is superposed,
(ii) at least the uppermost-level oxide superconducting layer of the multilayer structure includes a circuit element pattern,
(iii) the uppermost-level oxide superconducting layer, and the first oxide superconducting layer as another oxide superconducting layer of the multilayer structure, are made of an identical material, and
(iv) edges of the another oxide superconducting layer and the oxide insulating layer are a tapered surface reaching the insulating substrate, and the uppermost-level oxide superconducting layer is in direct contact with the tapered surface of the another oxide superconducting layer and the oxide insulating layer, and with an upper surface of the insulating substrate.
6. The superconducting device according to claim 5 , wherein
the insulating substrate is a bicrystal substrate, and
the Josephson junction is a bicrystal-type Josephson junction formed on the substrate.
7. The superconducting device according to claim 5 , wherein the circuit element is any one of a wiring and a coil.
8. The superconducting device according to claim 5 , wherein
the insulating substrate is a substrate having a step on a surface thereof, and
the Josephson junction is a step-edge type Josephson junction formed on the step of the substrate.