In Situ MOCVD of Dielectric Materials for High-T_c Superconducting Devices

Abstract

Devices which utilize high-T_c superconducting films require dielectric materials with low dielectric losses (tan δ), low dielectric constants, chemical inertness, and similar coefficients of thermal expansion to HTS materials. A major advance in the fabrication of such devices would be the deposition of high quality dielectric films by MOCVD (metal-organic chemical vapor deposition) which would enable the efficient, large-scale fabrication of multilayer superconductor-insulator structures. In this paper, we report the MOCVD deposition of epitaxial thin films of various pervoskite HTS lattice-matched dielectric materials: NdGaO₃, PrGaO₃, YA1O₃, and Sr₂AlTaO₆. These pervoskite dielectric films were grown in situ on single crystal substrates in a horizontal reactor using volatile metal-organic b-diketonate complexes as precursors. Film morphology and microstructure are characterized by SEM and cross-sectional TEM. Energy dispersive x-ray analysis is used to verify the stoichiometry. The crystallinity and epitaxy of the dielectric films are characterized by x-ray diffraction.