In situ growth of epitaxial YBa2Cu3O7 thin films by on-axis unbalanced direct current magnetron sputtering

Abstract

Superconducting YBa2Cu3O7−x thin films are prepared in situ by on-axis dc magnetron sputtering from a single stoichiometric target. The magnetron uses an unbalanced magnetic field configuration to eliminate resputtering effects, and high quality thin films on MgO (100) substrates are realized with excellent reproducibility. The target is sputtered in Ar/O2 mixture at a fixed partial pressure ratio pAr/pO2= 15:1. We report on the growth and properties of films deposited (a) as a function of the total sputtering pressure pt (1–100 Pa) at fixed substrate heater temperature Ts=740 °C, and (b) as a function of Ts (600–860 °C) at fixed pt=42 Pa. Epitaxial c-axis thin films are obtained over a wide range of deposition conditions (Ts≥700 °C, pt≥30 Pa). These films have superconducting transition temperatures Tc=86–90 K, critical current densities Jc77≥106 A cm−2, and resistance ratios R300/R100=2.0–3.1.

Metallization and interconnection of HTS YBCO thin film devices and circuits

“…Most of the YBCO films were grown on 10 × 10 mm 2 MgO substrates by dc magnetron sputtering from a sintered target of stoichiometric YBCO, followed by in situ annealing in oxygen [14]. The YBCO films used in the in situ contact samples were deposited via thermal co-evaporation by Theva GMBH.…”

Structural distortion and suppression of superconductivity in stoichiometricB1−MoNepitaxial thin films

“…1,2 ␥-Mo 2 N is known as a superconductor with T c ϳ 5 K. 3 We reported that ␤-Mo 2 N is also a superconductor with T c ϳ 5 K. 4 It was reported that the hexagonal ␦-MoN was crystallized in a slightly distorted NiAs type structure under 6 GPa, 5,6 and the resulting phase showed superconductivity with T c ϳ 12 K. 3,5 A theoretical study predicted that MoN with the cubic NaCl type structure ͑so called B1-MoN͒ would have T c as high as 29 K. [7][8][9][10] Since B1-MoN is believed to be a metastable phase, many studies adopted thin film deposition techniques, such as magnetron sputter, ion-beam assisted deposition, and ion implanting for the synthesis of the phase. [11][12][13][14][15][16][17] The B1-MoN films reported in the literature, however, have not exhibited such "high T c ." Later, theoretical studies predicted the elastic instability of the B1-MoN cubic structure, and suggested that orthorhombic, tetragonal or trigonal distortions would be more preferable.…”

Displacive phase transition, structural stability, and mechanical properties of the ultra‐incompressible and hard MoN by first principles

“…Due to the high superconducting transition temperature and hardness, good thermal and electronic conductivity, as well as chemical stability, molybdenum nitrides, in particular molybdenum mononitrides, have caused particular interest both theoretically and experimentally 1–23. Experimentally, bulk molybdenum nitride was known to exist only in hexagonal forms.…”

“…176) 3. Besides the bulk materials, high‐ T c superconductor MoN film in NaCl structure was also synthesized by dc‐magnetron sputtering 10, reactive magnetron sputtering 11, and low‐energy ion‐assisted deposition 12.…”