MOCVD of TlBaCaCuO on MgO Using Fluorinated Beta-Diketonate Source Reagents

摘要

Superconducting Tl2Ba2CaCu2Ox films were fabricated using a three step process.In the first step, amorphous BaCaCuOF films were deposited on MgO(100) single crystal substrates by metalorganic chemical vapor deposition at 500 C using fluorinated beta-diketonate complexes of Ba, Ca, and Cu. The fluorine was stripped from the BaCaCuOF films in the second step by annealing in wet O2 at 785 C. C-axis oriented Tl2Ba2CaCu2Ox films were formed in the final step by annealing the BaCaCuO in dry O2 at temperatures between 850 and 900 C in the presence of Tl2O3Ba2Ca2Cu3Ox pellets. The physical properties of the films were characterized by SEM, XRD, and RBS, and the electrical properties were evaluated with four point probe and microwave cavity measurements. Resistive transitions as high as 109K have been obtained. The best films showed critical current density as high as 10,000 A/sq cm at 90K and surface resistances 1/2 to 1/5 that of a gold standard at 17 GHz and 77K.