Superconducting Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub 8/ thin films prepared by post-annealing in a flow-through multiple-zone furnace

摘要

Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub 8/ thin films mere prepared first time by use of a multiple-zone flow-through thallination process. Thallous oxide was volatilized from condensed thallium oxide in a low temperature source zone and convectively transported to a higher temperature thallination zone in which initially amorphous Ba/sub 2/CaCu/sub 2/O/sub 5/ precursor films were located. By careful control of the source temperature, film temperature, flow rate, anneal time, and rates of heat up and cool down, smooth Tl/sub 2/Ba/sub 2/CaCuO/sub 8/ thin films ware prepared on [100] LaAlO/sub 3/ with the following properties: inductive T/sub c/ of 107.6 K and 80% transition width of 1.3 K, transport J/sub c/ at 75 K of 1.3/spl times/10/sup 5/ A/cm/sup 2/, and R/sub s/ at 10 GHz and 80 K of 1.3 m/spl Omega/. The scalability of the process to large area film processing was demonstrated by the preparation of Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub 8/ thin films on LaAlO/sub 3/ three-inch diameter wafers.