CRITICAL-CURRENT DENSITY AND RESISTIVITY MEASUREMENTS FOR LONG PATTERNED LINES IN TL2BA2CACU2O8 THIN-FILMS

Epitaxial Tl2Ba2CaCu2O8 films of thickness 0.65+/-0.05 mum and T(c) of 105+/-1 K were prepared on (100) LaAlO3 through a two-step post-deposition thallination process and patterned by standard photolithographic techniques and ion beam milling. Using the voltage per unit length criteria E(c)=1.0 muV/cm, transport critical current density J(c) in zero applied field for a 1.8-m-long, 12+/-1-mum-wide meander line separated by 8+/-1 mum spaces was measured to be 1.04 X 10(7) A/cm2 at 20 K, 1.82 X 10(6) A/cm2 at 80 K, and 1.02 X 10(5) A/cm2 at 100 K. The uniformity in J(c) was measured for eight line segments of about 11.7 cm length, yielding variations in J(c) of 1.44-3.02 X 10(6) A/cm2 at 80 K. J(c) values independent of linewidth were also measured for three 0.7-cm-long lines with widths of 7, 27, and 52 mum. For design of electronic circuits, resistivity may be a more useful design parameter than J(c), and detailed measurements of resistivity rho as a function of current density J were carried out. At low temperatures (T/T(c) < 0.2), rho increased by about two orders of magnitude for a 1 0% increase in J, and J(c) is well defined. At high temperatures (T/T(c) > 0.7), rho is less strongly dependent on J near J(c). At 90 K, where J(c)=7.6 X 10(5) A/cm2, rho remained less than 10(-10) OMEGA cm (3000 X less than oxygen free high conductivity copper at 90 K) even for J=1.4 X 10(6) A/cm2. The results suggest the potential for the use of patterned Tl2Ba2CaCu2O8 filmS in high J(c) electronic applications such as chip-to-chip interconnects operating at temperatures below 90 K.