Korean Institute of Surface Engineering

pISSN : 1225-8024 | eISSN : 3399-8403


공학

한국표면공학회지 (29권5호 415-423)

THIN FILM TECHNOLOGIES RELATED TO THE HIGH T$_{c}$ SUPERCONDUCTORS


Ri, Eui-Jae;


Korean Academy of Industrial Technologies;

Abstract

Thin film technologies for fabricating SQUIDs involve etching and deposition procedures with the proper substrate materials and $YBa_2Cu_3O_{7-d}$ (YBCO) as the high $T_c$ superconductor. YBCO were prepared on various substrates of MgO, $SrTiO_3$, and $LaAlO_3$ by using off-axis magnetron sputtering methods and annealing in-situ. The parameters of film fabrication processes had been optimized to yield good quality films in terms of the critical temperature $T_c$ and the critical current density $J_c$. The optimized processes yielded $T_C$>90K along with $J_c$>$10_6A$$extrm{cm}^2$ at 77K and>$2 imes10_7A/Cm^2$ at 5K. We fabricated step-edge type dc-SQUIDs and directly coupled magnetometers, producing step edges on MgO(100) substrates by etching with Ar-ion beam, depositing YBCO material on them, then patterning them by using ion-milling technique. Circuitizing washer-shape SQUIDs to possess a pair of step-edge junctions of 2-5$mu$ line width with a high angle>$50^{circ}C$ , we examined their I-V characteristics thoroughly and Shapiro steps clearly as we irradiate microwaves of 8-20 GHz frequency.

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