PRESERVATION OF SUBSTRATE CRYSTAL AND ENHANCEMENT OF YBA2CU3O7-X THIN-FILM GROWTH USING YSZ SI3N4 AS A BUFFER LAYER

Enhancement of high temperature super conducting YBa2Cu3O7-x (YBCO) thin film growth on GaAs and preservation of the substrate crystal were successfully realized using yttrium-stabilized ZrO2 (YSZ)/Si3N4 as a buffer layer. Highly c-axis oriented YBCO thin films with a zero resistance temperature as high as 85.5 K were obtained due to the use of a sub-top buffer of YSZ. The preservation of the GaAs surface at a temperature as high as 700-degrees-C in an oxygen-rich ambient, as revealed by photoreflectance measurement on the GaAs surface after removing YBCO, YSZ, and Si3N4 layers. was realized owing to the use of a sub-bottom buffer of Si3N4. Material analysis using a combination of cross-sectional scanning electron microscopy and Auger electron spectroscopy depth profiling demonstrated quite weak interdiffusions among different regions. The electrical and structural properties of both the YBCO film and the GaAs substrate after YBCO thin film deposition are believed to be the best reported so far.