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Epitaxial CeO2 buffer layers and YBa2Cu3O7−δ thin films have been grown in situ on (11̄02) sapphire by electron beam evaporation. Buffer layers of only 20 nm thickness inhibit interdiffusion between YBa2Cu3O7−δ and Al2O3 as determined by depth profiling using x-ray photoelectron spectroscopy. The layers show smooth surfaces and narrow interfaces. High lattice perfection of the CeO2 layer has been shown by x-ray diffraction. Laue oscillations up to ninth order have been observed in thin CeO2 buffer layers on sapphire. We found only one epitaxial orientation with YBa2Cu3O7−δ (001) ∥ CeO2 (001) ∥ Al2O3 (11̄02) and YBa2Cu3O7−δ [110] ∥ CeO2 [100] ∥ Al2O3 [112̄0]. YBa2Cu3O7−δ films grown on these buffer layers reveal Tc=88±0.5 K, ρ(300 K)=380 μΩ cm, and jc(77 K, 0 T)=1.3×106 A/cm2.

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Articles you may be interested inComposition dependence of microwave properties of YBaCuO thin films grown by metalorganic chemical vapor deposition Thinfilm growth and compositional effects in YBa2Cu3O7−x layers prepared by metalorganic chemical vapor deposition Preparation of aaxis oriented Y1Ba2Cu3O7−δ films by laser metalorganic chemical vapor deposition Appl. Phys. Lett. 59, 860 (1991); 10.1063/1.105260 Reduced thermal budget processing of Y-Ba-Cu-O high temperature superconducting thin films by metalorganic chemical vapor deposition J. Vac. Sci. Technol. A 9, 401 (1991); 10.1116/1.577421 Superconducting thin films of YBaCuO prepared by metalorganic chemical vapor deposition

A large excess of noise above that expected on the basis of thermal fluctuations has been observed in the output of thin-film Sn superconducting bolometers. The noise spectrum has been measured from 50 Hz to 4 MHz, with an additional measurement at 30 MHz as a function of applied magnetic field. The excess noise in the 100 KHz to 30 MHz range is found to be damped by the application of a perpendicular field of from 3 to 15 G. There is a l// 2 component at lower frequencies which is believed to be due to the detection of acoustic bubbling in the liquid helium. This portion of the noise was not affected by the application of a magnetic field.