Mocvd Routes To Thin Films For Superconducting Applications. Precursor Synthesis and Film Processing Issues

Abstract

ABSTRACTLow 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 Å. 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 YBa2Cu3O7−, 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 Tc = 87.3 K and 84.5 K for the LaSrGaO4 and PrSrGaO4 systems, respectively.