In situ preparation of superconducting Y1Ba2Cu3O7−δ thin films by on-axis rf magnetron sputtering from a stoichiometric target

Abstract

Superconducting Y1Ba2Cu3O7−δ thin films have been fabricated in situ by on-axis rf reactive magnetron sputtering from a single stoichiometric 1-2-3 target. By using high total sputtering pressures (≳400 mTorr) and low oxygen pressures (≤10 mTorr), negative ion resputtering is almost eliminated and high quality oriented films on (100)MgO are realized with excellent reproducibility. Such films display zero resistance Tc’s as high as 88 K with transition widths ΔTc (90%–10%) of about 2 K, residual resistivity ratios R(300 K)/R(100 K) of 2.5, and critical current densities greater than 106 A/cm2 at 14 K.

Stoichiometry control of magnetron sputtered Bi2Sr2Ca1−xYxCu2Oy (0⩽x⩽0.5) thin film, composition spread libraries: Substrate bias and gas density factors

“…It is widely accepted that oxygen has to be added to the sputtering gas for the deposition of Bi 2 Sr 2 CaCu 2 O 8+δ (Bi-Ca-2212) thin films [1,2,3,4]. The drawback to using oxygen in the sputtering gas is a pronounced resputtering of the deposited film, as found in Bi-Ca-2212 [5,6] and YBa 2 Cu 3 O 7−δ [7,8,9,10,11] superconducting systems. Oxygen anions derived from the sputtering gas and target material are the source of this resputtering effect [12].…”

“…Rather, the substrate is placed at an angle < 90 o relative to the axis of the cylindrical target. It has been found that the energy of oxygen anions that strike the film is reduced [1,5,6,7,8,9,10,11]. Off-axis sputtering greatly reduces the deposition rate, which is not desirable.…”

“…The energy of the anions is thereby decreased; however, the increased gas pressure also decreases the film deposition rate due to target atom-gas collisions. A third method to compensate for resputtering is to alter the target stoichiometry to account for the non-uniform depletion of elements [5,7,9]; this is sometimes not possible as the required target composition may not be an equilibrium phase. A final method uses a negative bias shield or substrate bias to deflect the anions away from the deposited film [1,3].…”

Superconductors: Processing of High‐ T C Bulk, Thin Film, and Wires

“…• )], is not deleterious to J c (18). However, the elimination of high-angle grain boundaries in HTS materials has been a difficult challenge to overcome.…”

Epitaxial MgO buffer layers for YBCO thin films onR-plane

“…Since the discovery of high-T c superconductors, highquality thin films have been prepared on oxide singlecrystal substrates such as MgO and SrTiO 3 [1][2][3][4]. These substrates are not suitable for device applications because they are not available in large sizes at low cost.…”