Al films as buffer layers for high-temperature superconducting thin films on amorphous substrates

We have prepared c-axis oriented YBa2Cu3O7-y (YBCO) thin films on amorphous substrates, such as SiO2 and soda potassium glass, by using Al(111) buffer layer. Before preparation of YBCO film, Al surface was oxidized at a subst rate temperature of 590 degrees C under (O-2+O-3;8%) atmosphere of 1 mTorr. This AlOx was amorphous state according to X-ray diffraction (XRD) and ref lection high-energy electron diffraction (RHEED) measurements. YBCO films w ere formed on amorphous substrates with the AlOx/Al layer using an ArF exci mer laser deposition technique. The vacuum pressure and substrate temperatu re during deposition were typically 1 mTorr and 590 degrees C, respectively .XRD measurements indicate that all the YBCO films were predominantly orien ted with the c-axis normal to the substrate surface. These results show tha t the AlOx plays a role of buffer and seed layer which has periodic potenti al of atomic order corresponding to Al(111) plane. Critical temperature T-c (zero) of the c-axis oriented YBCO film on AlOx/Al/glass substrate was 75K. This technique can be applied to other oxide material such as ferroelectri c and ferromagnetic materials and is very useful to applications.