High-speed operation of quasi-one junction superconducting quantum interference device based on high-Tc multilayer technology

Sugiyama, H.; Wakana, H.; Adachi, Seiji; Tarutani, Y.; Tanabe, K.

doi:10.1063/1.1690496

Cited by 14 publications

(6 citation statements)

References 15 publications

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“…These projected performances are owing to the high of the oxide electrodes and a high output voltage of the ramp-edge junction having a high critical current density , respectively. In reality, operating frequencies more than 100 GHz have been demonstrated for a toggle flip-flop(t-FF) [2] and comparators [3], [4]. The operating frequencies have been estimated from the voltage induced by the SFQs that successively propagate in the Josephson transmission line (JTL).…”

Section: Introductionmentioning

confidence: 99%

Fabrication and Logic Operation of Oxide SFQ-Circuit-Components

Tarutani

Ishimaru

Wakana

et al. 2005

IEEE Trans. Appl. Supercond.

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Basic SFQ circuit components, such as SFQ-dc converter, set-reset flip-flop (RS-FF), confluence buffer and splitter, have been fabricated by the YBa 2 Cu 3 O 7 x -ramp-edge-junction technology and their logic operations were investigated. Circuit parameters were optimized in order to widen the margins of these oxide SFQ circuit components. The SFQ-dc converter that comprised double SQUIDs connected in series showed the output voltage as much as 0.3 mV at 22 K owing to high value of the ramp-edge junction. Logic operations of the RS-FF, the confluence buffer and the splitter were correctly performed by using the SFQ-dc converter. Finite operating margins were obtainable for these circuits up to the temperature near 30 K. Index Terms-Confluence buffer, oxide SFQ circuit, RS flip-flop, SFQ-dc converter, splitter, YBa 2 Cu 3 O 7 x ramp-edge junction.

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Section: Introductionmentioning

confidence: 99%

Fabrication and Logic Operation of Oxide SFQ-Circuit-Components

Tarutani

Ishimaru

Wakana

et al. 2005

IEEE Trans. Appl. Supercond.

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“…The run-to-run spread of the average junction and the sheet inductance of both the base-and counter-electrodes for three samples was 12%, 3.0%, and 3.4%, respectively, which are substantially smaller than those previously reported [2], [13]. In samples fabricated by using this multilayer process, operation of several types of elementary SFQ circuits such as a QOS comparator [14], SFQ-dc converter [15] and confluence buffer [16] has been successfully demonstrated.…”

Section: Reproducibility Of Junction Propertiesmentioning

confidence: 87%

“…We previously fabricated ramp-edge junctions on ground planes made of (YBCO) liquid phase epitaxy (LPE) films with high crystallinity comparable to single crystals and atomically flat surfaces [9]. Although the junctions exhibited a high product of 1.1 mV at 40 K and a small spread of 8.1% for a 100-junction array, it is difficult to partially remove the ground plane for high-speed input or output lines because the LPE films are very thick (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) ). In the present study, we have fabricated multilayer structures including thin film ground planes for SFQ circuits.…”

Section: Introductionmentioning

confidence: 99%

Improvement in Reproducibility of Multilayer and Junction Process for HTS SFQ Circuits

Wakana

Adachi

Kamitani

et al. 2005

IEEE Trans. Appl. Supercond.

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We have developed an HTS multilayer structure including a superconducting ground plane and interface-engineered ramp-edge Josephson junctions for single flux quantum (SFQ) circuits, and tried to improve reproducibility in the multilayer and junction process. We found that one of the crucial factors to improve the reproducibility is use of a ground plane with small average surface roughness ( a ) of typically less than 2 nm and a high c above 87 K. By employing La 0 2 Y 0 9 Ba 1 9 Cu 3 O (La-YBCO) thin films deposited by dc off-axis magnetron sputtering, such high quality was maintained for 3-month successive use of a ceramic target. Use of such a high-quality ground plane reproducibly led to SrSnO 3 La YBCO SrSnO 3 La YBCO //MgO multilayer structures with a 2 nm and 100-junction arrays with 1 c spread of 6-17% at 4.2 K depending on the average c level. The run-to-run reproducibility of average junction c and sheet inductance of both the base-and counter-electrodes for three samples was 12%, 3.0%, and 3.4%, respectively, which are substantially smaller than those previously reported.

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“…These superconducting properties seem high enough for operating high-T c digital devices at around 40 K, which is a typical operating temperature of the devices presently studied. [1][2][3] It was found also that the La-YBCO thin films on BaZrO 3 prepared in the way described above have an advantage of high reproducibility over La-YBCO on MgO. The surface of a sputtering target tends to deteriorate after repeated deposition.…”

Section: B Optimization Of Deposition Conditionmentioning

confidence: 99%

Improvement in Crystal Orientation and In-plane Alignment of La-doped YBCO Thin Film on BaZrO₃-buffered MgO Substrate

et al. 2005

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Y 0.9 Ba 1.9 La 0.2 Cu 3 O y (La-YBCO) thin films were prepared by an off-axis magnetron sputtering method on MgO substrates with and without a BaZrO 3 buffer layer. Insertion of BaZrO 3 buffer layer was effective for obtaining La-YBCO films with pure c-axis orientation and in-plane alignment at low temperatures below 600°C. We prepared La-YBCO thin films on BaZrO 3 -buffered MgO substrates using a temperature-gradient method, in which a template La-YBCO layer was first deposited at 600°C, and then the temperature was continuously raised to 700°C. By this method, La-YBCO thin films with improved crystallinity were successfully prepared. It was also proved that the insertion of the BaZrO 3 buffer layer enables us to prepare high-quality La-YBCO films with high reproducibility.

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High-speed operation of quasi-one junction superconducting quantum interference device based on high-Tc multilayer technology

Abstract: Store-restore operation of flux quanta in coplanar type high T c superconductive quantum interference devices

Cited by 14 publications

References 15 publications

Fabrication and Logic Operation of Oxide SFQ-Circuit-Components

Fabrication and Logic Operation of Oxide SFQ-Circuit-Components

Improvement in Reproducibility of Multilayer and Junction Process for HTS SFQ Circuits

Improvement in Crystal Orientation and In-plane Alignment of La-doped YBCO Thin Film on BaZrO₃-buffered MgO Substrate

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High-speed operation of quasi-one junction superconducting quantum interference device based on high-Tc multilayer technology

Abstract: Store-restore operation of flux quanta in coplanar type high T c superconductive quantum interference devices

Cited by 14 publications

References 15 publications

Fabrication and Logic Operation of Oxide SFQ-Circuit-Components

Fabrication and Logic Operation of Oxide SFQ-Circuit-Components

Improvement in Reproducibility of Multilayer and Junction Process for HTS SFQ Circuits

Improvement in Crystal Orientation and In-plane Alignment of La-doped YBCO Thin Film on BaZrO3-buffered MgO Substrate

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Improvement in Crystal Orientation and In-plane Alignment of La-doped YBCO Thin Film on BaZrO₃-buffered MgO Substrate