A YBCO multilayer process using surface-modified junction technology

Soutome, Y.; Fukazawa, T.; Saitoh, Kazuo; Tsukamoto, Akira; Takagi, K

doi:10.1109/tasc.2003.813955

Cited by 12 publications

(8 citation statements)

References 15 publications

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“…The interface-engineered junction (IEJ) [3] with a rampedge structure is a promising candidate for use in HTS integrated circuits, since small I c spreads were reported for such junctions [4,5]. However, the magnitude and the spread of I c have been found to significantly depend on various parameters including the surface roughness of the multilayers or the density of particles [6], and the deposition conditions for the counter-electrode [7].…”

Section: Introductionmentioning

confidence: 99%

Fabrication of high-temperature superconductor single-flux-quantum circuits using a multilayer structure with a smooth surface

Wakana¹,

Adachi²,

Tsubone³

et al. 2006

Supercond. Sci. Technol.

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We have developed a multilayer structure with a smooth surface and fabrication processes for HTS single-flux-quantum (SFQ) circuits. The multilayer structure with surface roughness R a less than 2 nm, composed of a La 0.2 -Y 0.9 Ba 1.9 Cu 3 O x ground plane and base electrode layer, and SrSnO 3 insulating layers, was deposited by off-axis magnetron sputtering. We have fabricated interface-engineered junctions based on the multilayer structure using an La 0.2 -Yb 0.9 Ba 1.9 Cu 3 O x counter-electrode layer prepared by pulsed laser deposition. The fabricated junctions exhibited excellent Josephson characteristics with a 1-σ spread in I c as low as 8% for 1000 junctions. The sheet inductance values below 50 K were 0.8-1.0 pH per square. Operation of several elementary SFQ circuits including a toggle flip-flop, a confluence buffer, a set-reset flip-flop and other SFQ elements has been successfully demonstrated at 30-60 K.

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Section: Introductionmentioning

confidence: 99%

Fabrication of high-temperature superconductor single-flux-quantum circuits using a multilayer structure with a smooth surface

Wakana¹,

Adachi²,

Tsubone³

et al. 2006

Supercond. Sci. Technol.

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“…They have the advantages of low power consumption and high-speed operation at around 40 K, being much higher than the operation temperature of Nb circuits, that is 4.2 K. To realize HTS-SFQ devices, fabrication process of JJs integrated on a superconducting ground plane must be established. A few groups reported successful fabrication of JJs on the ground plane [2][3][4]. Excellent flatness and pure orientation are required for the lowest layer as a foundation of multilayer structures.…”

Section: Introductionmentioning

confidence: 99%

“…Excellent flatness and pure orientation are required for the lowest layer as a foundation of multilayer structures. Soutome et al [2] used a YBa 2 Cu 3 O y thin film for the ground plane. It requires the stoichiometric cation ratio to form mono-phasic films.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of 123‐type high‐ T _c superconducting thin films on BaZrO ₃ ‐buffered MgO substrates

Adachi

Wakana

Kamitani³

et al. 2006

Phys. Status Solidi (c)

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We have developed a stable preparation process for high-quality thin films of YBa 2 Cu 3 O y (123)-type high-T c superconductors (HTS) for the ground plane of single-flux-quantum (SFQ) devices. The films were deposited on MgO (100) substrates by an off-axis DC magnetron sputtering method. During deposition, the substrates were directly heated by thermal radiation from a heater. No adhesive paste was used for fixing the substrate. Possibility of chip contamination due to the paste could be completely eliminated. The insertion of a BaZrO 3 (BZO)-buffer layer was effective to obtain flat epitaxial 123 films with complete c-axis orientation. The flat ground plane could play a role as a suitable foundation for multilayer films of SFQ devices.

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“…YBa 2 Cu 3 O y (YBCO) is a widely studied high temperature superconducting (HTSC) material from interests in fundamental physics and chemistry, whereas YBCO thin films attracted much attention in applied research because of their capability of carrying large critical current and possible candidates for device applications. Trilayer-type junctions [1][2][3][4][5] as well as ramp-edge junctions [6][7][8][9][10][11] based on YBCO thin films have been reported. Sato et al recently found that the modified barrier for YBCO trilayer junctions by sequential treatments, i.e., argon plasma bombardment, vacuum annealing and exposure to ozone show resistively and capacitively shunted junction (RCSJ) like currentvoltage characteristics.…”

Section: Introductionmentioning

confidence: 99%

Modification of YBa₂Cu₃O_y Thin Films by Exposure to Argon Plasma and Ozone: A Structural Study

Mohamed

Ōyanagi

Fukano

et al. 2005

Jpn. J. Appl. Phys.

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The effects of argon plasma bombardment and subsequent heat treatments on the structure of YBa2Cu3O y thin films were studied. We find that the argon plasma processing modifies the yttrium composition through the formation of Y2O3 islands (serving as an yttrium reservoir) and solid-state diffusion. The scanning electron microscopy (SEM) images show that the argon plasma bombardment accelerates the growth of Y2O3 islands which are thinned and washed away during the subsequent annealing in vacuum. Complimentary techniques (X-ray diffraction and X-ray absorption spectroscopy) show that the structural disorder caused by argon plasma processing is recovered by heat treatment in vacuum while oxygen vacancies are compensated by the final ozone treatment. The results reveal the individual roles of sequential treatments of YBa2Cu3O y thin films which improve the electrical properties of ramp-edge Josephson junctions.

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A YBCO multilayer process using surface-modified junction technology

Cited by 12 publications

References 15 publications

Fabrication of high-temperature superconductor single-flux-quantum circuits using a multilayer structure with a smooth surface

Fabrication of high-temperature superconductor single-flux-quantum circuits using a multilayer structure with a smooth surface

Fabrication of 123‐type high‐ T _c superconducting thin films on BaZrO ₃ ‐buffered MgO substrates

Modification of YBa₂Cu₃O_y Thin Films by Exposure to Argon Plasma and Ozone: A Structural Study

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A YBCO multilayer process using surface-modified junction technology

Cited by 12 publications

References 15 publications

Fabrication of high-temperature superconductor single-flux-quantum circuits using a multilayer structure with a smooth surface

Fabrication of high-temperature superconductor single-flux-quantum circuits using a multilayer structure with a smooth surface

Fabrication of 123‐type high‐ T c superconducting thin films on BaZrO 3 ‐buffered MgO substrates

Modification of YBa2Cu3Oy Thin Films by Exposure to Argon Plasma and Ozone: A Structural Study

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Product

Resources

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Fabrication of 123‐type high‐ T _c superconducting thin films on BaZrO ₃ ‐buffered MgO substrates

Modification of YBa₂Cu₃O_y Thin Films by Exposure to Argon Plasma and Ozone: A Structural Study