MOCVD routes to thin films for superconducting applications. Precursor synthesis and film processing issues

Low pressure metal-organic chemical vapor deposition has been used to grow dielectric thin films of the tetragonal perovskites LaSrGaO₄ and PrSrGaO₄ on (110) LaAlO₃ using the volatile metal sources Pr(dpm)₃, La(hfa)₃·tri, Ga(dpm)₃, and Sr(hfa)₂·tet (dpm = dipivaloylmethanate, hfa = hexafluoroacetylacetonate, tet = tetraglyme, and tri = triglyme). The PrSrGaO₄, a new ternary oxide, was found to have a body-centered tetragonal lattice with a = b = 3.80 and c = 12.59 angstrom. Epitaxial c-axis oriented growth of these materials has been revealed by both x-ray and electron diffraction, with an average surface roughness, measured by AFM, of 1.2 nm for LaSrGaO₄ and 3.0 nm for PrSrGaO₄. In addition to this, the ability of these materials to function as lattice-matched buffer layers for the growth of the high temperature superconductor YBa₂Cu₃O_7-x has been explored. The superconductive properties of the YBCO layer do not indicate any degradation attributable to the buffer layers, with the onset of superconductivity displaying a sharp metal-superconductor transition at T_c = 87.3 K and 84.5 K for the LaSrGaO₄ and PrSrGaO₄ systems, respectively.