MOCVD ROUTES TO TL(2)BA(2)CA(N-1)CU(N)O(4-FILMS(2N)SUPERCONDUCTOR ANDDIELECTRIC INSULATOR THIN)

The evolution of HTS device technologies will benefit from the develop ment of MOCVD (Metal-organic Chemical Vapor Deposition) routes to high quality HTS films as well as to those of insulators with low dielectr ic loss and close HTS lattice matches. Reviewed here are research effo rts at precursor design focusing on Ba sources. A novel low pressure T GA technique is used to compare volatilities of MOCVD precursors and t o quantify the role of gas phase diffusion in film growth. To form hig h quality Tl2Ba2Can-1CunO4+2n (n = 2,3) films, BaCaCuO(F) films are fi rst deposited by MOCVD using the liquid precursors Ba(hfa)(2) . mep, C a(hfa)(2) . tet, and solid Cu(dpm)(2) (hfa = hexafluoroacetylacetonate , dpm = dipivaloylmethanate methylethylpentaglyme, tet = tetraglyme). The film growth process is shown to be mass transport-limited, and an interesting ligand exchange process is identified. The superconducting TBCCO phase is formed following an ex-situ anneal in the presence of Tl2O at temperatures from 820-900 degrees C. Transport properties of T BCCO-2223 films include a T-c as high as 115K, J(c) of 2x10(5) A/cm(2) (77K), and R(s) of 0.35m Omega (5K, 10 GHz). The MOCVD growth of low loss, lattice-matched dielectric NdGaO3, PrGaO3, Sr2AlTaO6 and SrPrGaO 4 films is also discussed. High quality YBa2Cu3O7-x films have been gr own upon MOCVD-derived PrGaO3 substrates.