PREPARATION OF SR1-XLAXCUO2-DELTA FILMS BY METALORGANIC CHEMICAL-VAPOR-DEPOSITION

Thin films of infinite-layered tetragonal Sr1-xLaxCuO2-delta (x = 0.08 similar to 0.12) phases were deposited on SrTiO3(100) substrate by metalorganic chemical vapor deposition (MOCVD). Fabrications of c-axis oriented films on NdGaO3(100) and LaAlO3(100) were also carried out. Solubility limit of this phase is x 0.11 which is similar to that of high pressure synthesis. Lattice parameter, c, decreases with increasing x with fixed oxygen partial pressure during the growth. For the film of Sr0.985La0.085Cu2-delta, the c-axis lattice constant changed from c = 3.5905 Angstrom to c 3.433 Angstrom depending upon oxygen partial pressure. No superconductivity was observed for the epitaxial films with the c-axis lattice constant minimum at 3.420 Angstrom. Lattice constants of the MOCVD grown thin films are different from those of high pressure stabilized bulk phases due to strains induced at interface. The decrease of c parameters with reductive condition during the growth process of the infinite-layered tetragonal Sr1-xLaxCuO2-delta thin films indicated that complete removal of apical oxygen is required to induce n-type superconductivity.