Growth direction control YBCO thin films

✍ Scribed by F. Vassenden; G. Linker; J. Geerk

• Book ID: 103943747
• Publisher: Elsevier Science
• Year: 1991
• Tongue: English
• Weight: 535 KB
• Volume: 175
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(91)90265-z

✦ Synopsis

The crystallographic orientation of thin films of YiBa2Cu307 (YBCO) on MgO and SrTiO 3 was investigated with 0--20 X-ray diffraction. The fraction of a-axis oriented material was measured as a function of substrate temperature during growth. Films prepared at substrate table temperatures yielding maximum Tc were purely c-axis oriented up to a critical film thickness ( < 5500

), above which also a-axis material was observed. Our hypothesis was that the substrate temperature is lowered during deposition due to the increasing emissivity of the film as it reaches a thickness comparable with the IR penetration depth, and that this lowered substrate temperature makes a-axis growth possible. We estimated this cooling effect, and found that it was too small to allow for a-axis oriented growth. The cooling hypothesis is contrasted to a-axis oriented growth caused by an increased density of lattice imperfections with growing film thickness.