IN-SITU GROWN SUPERCONDUCTING YBCO FILMS ON BUFFERED SILICON SUBSTRATES FOR DEVICE APPLICATIONS

Thin films of YBa2Cu3O7-delta (YBCO) have been grown in situ on silico n single-crystal (100) substrate by using SrTiO3 as a buffer layer. Th e deposition has been carried out by on-axis rf magnetron sputtering m ethod. The deposition condition have been optimized by studying the pl asma characteristics and correlating them with the superconducting per formance of the film. Films deposited at substrate temperature in the range of 680-700 degrees C from stoichiometric YBCO targets in an argo n + oxygen mixture (3:1) are superconducting and show c-axis epitaxy. Compositional confirmation has been carried out using Rutherford backs cattering. Scanning tunneling microscopy of the films reveal formation of well-defined layered structure with some defects in the initial st ages of in situ growth of the films. Films grown on SrTiO3 substrates have excellent crystalline quality (XRD), transition temperature T-c0= 81 K and the critical current density J(c)>2 x 10(5) A/cm(2) for unpat terned films at 77 K. On silicon substrates using buffer layers the in situ deposited YBCO films shows a higher transition width and T-c0 is also slightly less (71 K).