Superconducting Films of YBCO on Bare Silicon
We have prepared thin films of superconducting YBa2Cu3O7 on bare silicon (100) by thermal coevaporation of yttrium, barium and copper in an oxygen atmosphere. The highest temperature attained in the process is about 650°C, the temperature of the heated substrate. No post-deposition anneal is necessary to achieve superconductivity at 80 K and critical current densities, at 4.2 K, of 9 × 104 Acm-2. In the best case so far, the YBCO film was superconducting at 85 K on bare Si after a short post anneal at 480° C. X-ray diffraction studies show that the best films are oriented with the c-axis perpendicular to the substrate, with no trace of reflections corresponding to other than those from (00l) planes. We have also produced superconducting YBCO films on Si substrates with buffer layers of amorphous SiO2 and amorphous Si3N4. These films are also largely c-axis oriented. The best superconducting characteristics were transition temperatures of 68 – 69 K and critical current densities at 4.2 K of 3 × 103 Acm-2.
KeywordsBuffer Layer Critical Current Density YBCO Film Cuprate Superconductor Bare Silicon
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