In-Plane Texturing of Buffer Layers by Alternating Beam Assisted Deposition: Large Area and Small Area Applications
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1150-RR05-02
In-Plane Texturing of Buffer Layers by Alternating Beam Assisted Deposition: Large Area and Small Area Applications
Alexander Usoskin and Lutz Kirchhoff Bruker High Temperature Superconductors GmbH, Siemensstr. 88, D-63755 Alzenau, Germany
ABSTRACT In standard ion beam assisted deposition (IBAD), the growing film is exposed to inclined ion etching in order to achieve a preferable in-plane orientation of the crystalline structure. Recently, we suggested exposing the film periodically to deposition pulses and to etching pulses, i.e. to assisted beam pulses. As a long sequence of alternations of these two pulses is needed, we named this method “alternating beam assisted deposition” (ABAD). In real application, the substrates exposed to the molecular/atomic flow originating from the sputter source acquire a few nanometer thick layer of yttria-stabilized zirconia (YSZ). In the next step, this layer undergoes ion etching with an Ar ion beam emitted from the source with a particle energy between 200 and 300 eV. Simultaneously with ion-beam exposition, an additional electron beam provides neutralizing of the electrical change in the substrate plane. The ion beam guided 55° at a 55° angle of incidence provides selective etching of the YSZ layer, leading finally after numerous deposition-etching cycles to a sufficiently high quality of in-plane texture in the YSZ layer with the best FWHM values of 8°-9°.
INTRODUCTION The technology of high-temperature superconductors (HTS) of the second generation requires a biaxially textured template layer onto which the superconductor is deposited. These template buffer layers have to be lattice-matched, chemically compatible, and cost effective in long-lengths processing. At present ion-beam assisted deposition (IBAD) is widely used in the processing of such templates [1-6]. A different method utilizing alternation of the molecular beam and the ion beam, i.e. alternating ion beam assisted deposition (ABAD) [7], was recently suggested in order to improve the quality of the texture. In this study we describe the background of the ABAD process and also demonstrate different possibilities for ABAD application. One on these is deposition of in-plane textured layers onto wide flexible tape formed as closed loop. Another, more widespread application in template processing of long-length flexible tape is very important in the technology of HTS coated conductors [1-7]. As a special case, we also consider here the ABAD technique used in buffer template deposition across cylindrical substrates. Below we have cited test results which are obtained employing yttria-stabilized zirconia (YSZ) that facilitates a high degree of in-plane texture with characteristic full width at half-maximum (FWHM) of 8-11°.
ABAD The method we recently introduced in the processing of HTS coated conductors is based on a technique where the template film is periodically exposed to alternating deposition and etching pulses. A schematic view of a set-up developed for realization of this process with flexible
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