Microstructural studies on a high quality YBa2Cu3O7-δ/YSZ/Si multilayer prepared by pulsed-laser deposition

We demonstrated a new approach to fabricate high quality superconducting YBa2Cu3 O7-δ (YBCO) thin films on natively oxidized Si(100) wafers with an yttria-stabilized zirconia (YSZ) buffer layer. Perfect YSZ thin films were deposited on the Si wafer under ambient pressure of 10-7 mbar at the initial stage followed by 10-4 mbar, yielding a YSZ film with a root mean square roughness of only 0.3-0.5 nm. Clear and sharp interfaces were observed between YSZ and Si, and YBCO and YSZ. No obvious amorphous SiOx layer or BaZrOx layer were observed at these two interfaces, respectively. The missing SiOx layer was believed to be a result of the special deposition process. The epitaxial correlations of the YBCO/YSZ/Si multilayer were found to be YBCO(001)|| YSZ(100)|| Si(100) and YBCO[100]|| YSZ[011]|| Si[011]. The diffusion length of Si into the YSZ layer was only 40 nm. The perfect crystalline structure of the films as well as the absence of diffused Si in the YBCO layer resulted in a transition temperature Tc(0) as high as 87 K in the YBCO/YSZ/Si multilayers. The method may also be applied in the fabrication of other perovskite thin films on native Si wafers. (author)