Recovery Treatment of EuBa_2Cu_3O_<7-δ> Thin Films with Activated Oxygen Plasma

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概要

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• Using high-quality c-axis-oriented EuBa_2Cu_3O_<7-δ> (EBCO) thin films with transition temperatures (T_<ce>) of about 90 K, a deterioration treatment by removal of oxygen atoms and a recovery treatment were performed in a sputtering chamber. The removal of oxygen atoms by heating in a mixture gas of Ar+7.5%O_2 at 7 Pa resulted in an expansion of lattice constants (c_0) of about 11.86Å and semiconductive features. Two recovery methods using pure oxygen and activated oxygen plasma were examined. For the treatment with pure oxygen, signs of recovery in structural and transport properties appeared at annealing temperatures (T_<sa>) above 300℃ at an oxygen pressure (P_<O_2(a)>) of 30Pa, but the as-grown state was not obtained even at P_<O_2(a)>=2000 Pa. For the activated oxygen plasma treatment, where the deteriorated films were exposed to oxygen plasma and oxygen gas was subsequently introduced into the chamber, an almost complete recovery of superconducting and structural properties was achieved. The appropriate conditions for the recovery were T_<sa>'s of 500-700℃, plasma exposure time (t_p) above 30min, and oxygen partial pressures (P_<O_2(pc)>) above 200Pa. Atomic force microscope (AFM) images of EBCO films treated at T_<sa>'s below 550℃ showed the same spiral structure as those of as-grown films. The image-deformation and growth of outgrowths became obvious with increasing annealing temperature. The change in the surface morphology revealed the substantial movement of constituent atoms from T_<sa>'s of about 600℃. Because the films exhibit optimum superconducting properties in spite of the rapid cooling, it is considered that the movement of constituent atoms induces trilayered perovskite structures with an excess oxygen atom deficiency at high temperatures.

• 社団法人応用物理学会の論文
• 1999-12-15

著者

• Wakana Hironori

  Faculty Of Engineering Iwate University

• MICHIKAMI Osamu

  Faculty of Engineering, Iwate University

• Michikami Osamu

  Faculty Of Engineering Iwate University

• ATSUMI Koukichi

  Faculty of Engineering, Iwate University

• Atsumi Koukichi

  Faculty Of Engineering Iwate University

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• Recovery Treatment of EuBa_2Cu_3O_ Thin Films with Activated Oxygen Plasma
• Non-c-axis-Oriented EuBa_2Cu_3O_ Thin Films Grown on Al_2O_3(1102) Substrates with CeO_2 Buffer Layers
• EuBa_2Cu_3O_ Thin Films Grown on Sapphires with Epitaxial CeO_2 Buffer Layers
• Characteristcs of Ga-Doped ZnO Films Prepared by RF Magnetron Sputtering in Ar + H_2 Ambience
• Superconducting Properties of EuBa_2Cu_3O_7 Thin Films Deposited on R-Plane Sapphires with CeO_2＼Sm_2O_3 Buffer Layers Using Magnetron Sputtering(Recent Progress in Oxide Thin Films by Sputtering)
• Effect of Sputter Gas Pressure and RF Power on Surface Morphology of CeO2 Buffer Layers and Superconducting Properties of EuBa2Cu3O7-δ Thin Films by Magnetron Sputtering

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