Unbalanced magnetron sputter deposition of biaxially aligned yttria stabilized zirconia and indium tin oxide thin films

Developing a fast and flexible deposition process for biaxially aligned buffer layers on polycrystalline or amorphous substrates is still an important step toward the development of a scalable process for REBa₂Cu₃O_7-x (REBCO, RE(RareEarth) = Y, Nd,...) coated conductor. Biaxially aligned Yttria Stabilized Zirconia (YSZ) and Indium Tin Oxide (ITO) thin films were deposited using a specifically modified sputter magnetron. ITO could be an interesting alternative for YSZ as a buffer layer for REBCO, since it is an oxide materials with good electrical conductivity, the lattice matches with REBCO and it has more or less the same thermal expansion coefficient as REBCO. Conducting buffer layers are interesting for some applications. Some publications indicate that there is very little interaction between ITO and YBCO thin films. The layers were deposited in reactive DC sputter mode on glass and nonpolished Hastelloy substrates, at low pressure, with excellent adhesion and high deposition rate : deposition rates up to 75 nm/min were obtained for YSZ and up to 40 nm/min for ITO. The influence of some sputter parameters (e.g., pressure, target-to-substrate distance, ...) on the degree of biaxial alignment was investigated.