Growth of YBa2Cu3O7-χ Films on Si with Al2O3 Buffer Layer and on LiNb03 by In-situr Metalorganic Chemical Vapor Deposition?

We present deposition of superconducting YBazCu3O7-x, thin films on Si (100) substrate with an Al2O3 buffer layer and LiNb03 single crystal substrates by metalorganic chemical vapor deposition. Organomatallic sources of β-diketonate complexes of Y(dpm)3, Ba(dpm)2, Cu(dpm)2, and aluminum isopropoxide were used as yttrium, barium, copper, and aluminum precursors, respectively. A resistive heated vertical cold-wall reaction chamber using N2O gas as an oxidizer was successful for depositing thin films of YBa2Cu3O7-x and an epitaxial Al2O3 buffer layer without post annealing. A buffer layer of MOCVD grown Al2O3 film on silicon (100) was found to be a y phase Al2O3 hetero-epitaxial film from the X-ray diffraction analysis. An As-deposited film on Al2O3/Si(100) substrate at a substrate temperature of 800 ~ 850°C showed superconducting behavior at Tc,zero = 52 K. For YBa2Cu3O7-x/AI2O3/Si(100), the Al2O3 hetero-epitaxial buffer layer is a diffusion barrier between the superconducting film and the silicon substrate during high temperature growth. We also discuss in-situ MOCVD growth of an YBa2Cu3O7-x thin film on a z-cut LiNb03 single crystalline substrate showing Tc,zero = 85 K. in-situ formation of YBa2Cu3O7-x films on lattice mismatched LiNb03 substrate is useful for future integrated optical device applications.

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