DEPOSITION OF YBCO THIN-FILMS OVER LARGE AREAS BY A 90-DEGREES OFF-AXIS SPUTTERING TECHNIQUE

We report the deposition of YBCO thin films with uniform thickness (< +/- 5% variation), and stoichiometric composition (< 2.3% deviation fr om the target stoichiometry) over an 8 '' diameter area, by a single t arget 90 degrees off-axis sputtering technique using a 3 '' diameter t arget and optimized substrate rotation, A 3 '' diameter resistive heat er was used with optimized rotation in two consecutive deposition runs to study the variation in film properties of small test samples depos ited over an 8 '' diameter area, Due to the inherent temperature non-u niformity of the heater, all the samples could not be deposited under optimum growth conditions, However, all the films displayed a consiste ntly high transition temperature (T-c > 87.5 degrees K) and critical c urrent density (J(c) (77 K) > 1 x 10(6) A/cm(2), J(c) (4.2 K) > 1 x 10 (7) A/cm(2)) over an 8 '' diameter area, Considering only the better o ptimized samples the films displayed high critical current densities ( J(c) (77 K) > 3 x 10(6) A/cm(2), J(c) (4.2 K) > 3 x 10(7) A/cm(2)). Th e variations in the film properties have been correlated to the variat ions in crystalline quality, amount of c-axis grains and substrate tem perature during deposition.