Improvement of average film quality in RBa/sub 2/Cu/sub 3/O/sub 7-x/ sputtered films

Thin films of RBa/sub 2/Cu/sub 3/O/sub 7-x/ (R includes Y, Er, and Nd) have been deposited by four-gun DC magnetron sputtering from metallic targets in a Xe-O/sub 2/ gas mixture and postannealed in flowing O/sub 2/. Extensive optimization of the film deposition process has been achieved for erbium-based films which can be produced with good characteristics on a variety of substrates. Fine-grained polycrystalline films with sharp resistive transitions are produced on single-crystal and polycrystalline YSZ, MgO, ZrO/sub 2/-buffered sapphire, and silver-buffered sapphire. Broader transitions are observed on buffered silicon wafers. These erbium films often show grain sizes as small as 20-30 nm and, with the addition of an RF oxygen glow discharge in the deposition system, are quite smooth despite furnace postannealing. Highly-oriented 1-2-3 film growth is observed on SrTiO/sub 3/ and LaAlO/sub 3/ single-crystal substrates. Four-point resistivity measurements show transitions as narrow as 1 K, while magnetization and RF frequency-shift measurements show more detail about film quality. Films are characterized by XRD, SNMS, Auger, XPS, and cross-sectional EDX profiling. The authors also report on the use of in-situ deposition of silver as a passivation layer for the 1-2-3 surface.<
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