Synthesis of Yttrium Barium Copper Oxide Superconducting Thin Films by Metalorganic Chemical Vapor Deposition

Metalorganic Chemical Vapor Deposition (MOCVD) has been developed and optimized for the synthesis of high -T_{rm c} superconducting thin films. Several different processing approaches have been utilized to produce high quality Y-Ba-Cu-O films. Best results have been obtained by plasma-enhanced MOCVD, using activated N_2O as the oxidizing agent. Epitaxial Y-Ba-Cu-O thin films, with zero resistance temperature (T_{rm c}) of 90 K and critical current density (J_ {rm c}) of 2.4 times 10^6 A/cm^2 (77 K, 0 T) have been produced on (100) SrTiO _3 and (100) LaAlO_3 substrates. PE-MOCVD is also capable of producing c-axis oriented Y-Ba-Cu-O films, with T_{ rm c} of 85 K, on polycrystalline Ag substrates. Growth rate and composition effects on T _{rm c}, J_ {rm c}, and surface morphology have also been investigated. Low growth rates (<= 1000 A/hr) favor the formation of high quality films, with smooth surfaces. Off-stoichiometric copper-rich films exhibit superior superconducting properties. This research has demonstrated the feasibility of producing high quality Y-Ba-Cu-O films on ceramic substrates by MOCVD. Further research is needed to adapt this technology to commercially useful substrates, such as Si and GaAs.