Electron beam flash evaporation for YBaCuO and BiCaSrCuO thin films

Abstract

An electron beam flash evaporation technique is described which reproduces the stoichiometry of superconducting YBa2Cu3Ox (123), Bi2CaSr2Cu2Oy (2122), and Bi2Ca2Sr2Cu3Oz (2223) source powders. Films of each material deposited with this technique exhibit zero resistance temperatures of 78 K or above when furnace annealed; 75 K zero temperatures are obtained for 123 films in situ annealed with atomic oxygen at 775 °C. Transport critical current densities are 1×104 A/cm2 in 25-μm stripes patterned from 123 films, and 6×104 A/cm2 in 1-mm stripes of 2122 and 2223 films using a 1-μV/mm measurement criteria. Typical normal state resistivities are 700 μΩ cm for 2122 and 2223 films and 5 mΩ cm for 123 films. The 2122 films are highly textured with the c axis normal to the substrate. All results are for films deposited on MgO.