Magnetron Sputter deposition of a 48-member cuprate superconductor library: Bi2Sr2YxCa1-xCu2Oy (0.5 <= x <= 1) linearly varying in steps of 0.01

• Main Authors: Sanderson, R. J, Hewitt, K. C
• Format: Journal Article
• Language: English
• Published: 01-02-2007
• Subjects: Physics - Materials Science; Physics - Superconductivity
• DOI: 10.48550/arxiv.cond-mat/0702035

Using magnetron sputtering, a spatial composition spread approach was applied
successfully to obtain 48-member libraries of the Bi2Sr2YxCa1-xCu2Oy (0.5<= x
<=1)cuprate superconducting system. The libraries of each system were deposited
onto (100) single crystal MgO, mounted on a water cooled rotating table, using
two targets: the antiferromagnetic insulator Bi2Sr2YCu2Oy (P=98 W RF) and the
hole doped superconductor Bi2Sr2CaCu2Oy (P=44 W DC). A low chamber pressure of
0.81 mTorr argon is used to reduce scattering by the process gas. To minimize
oxygen resputtering a substrate bias of -20 V was used as well as a process gas
free of oxygen. A rapid thermal processor is used to post-anneal the amorphous
deposited films. A step annealing regime was used, with a ramp rate of 5
degrees C/s for heating and cooling, with a first plateau at 780 C held for 200
s, and a second at 875 C held for 480 s. X-ray diffraction reveals that the
films develop crystalline order with the c-axis lattice parameter contracting
linearly from 30.55 Angstroms (x=0.5) to 30.24 Angstroms (x=1.0) with
increasing Y-content, consistent with bulk values. The crystallized films are
polycrystalline, developing preferred orientation (c-axis parallel to the
substrate) for thinner members of the library. There is a change of 0.01 in
doping per library member which will enable further studies to densely map
phase space.