Magnetron sputter deposition of a 48-member cuprate superconductor library: Bi2Sr2YxCa1−xCu2O8+δ (0.5≤x≤1) linearly varying in steps of Δx=0.01

Using magnetron sputtering, a spatial composition spread approach was applied successfully to obtain 48-member libraries of the Bi2Sr2YxCa1−xCu2O8+δ (0.5≤x≤1) cuprate superconducting system. The libraries of each system were deposited onto (1 0 0) single crystal MgO, mounted on a water cooled rotating table, using two targets: the antiferromagnetic insulator Bi2Sr2YCu2O8+δ (P=98 W rf) and the hole doped superconductor Bi2Sr2CaCu2O8+δ (P=44 W dc). A low chamber pressure of 0.81 mTorr argon was 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 was used to post-anneal the amorphous deposited films. A step annealing regime was used, with a ramp rate of 5 °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 Å (x=0.5) to 30.24 Å (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.