Effects of Deposition Rate And Substrate Temperature On The Orientation And The Growth of Yba2Cu3OxThin Films

We report what we be1ieve to be the first real time, in-Situ studies of film growth by sputtering using synchrotron X-rays; the structure and growth habit of YBa2Cu3Ox (YBCO) thin films deposited on (100) SrTiO3in a miniature, faced-magnetron sputtering system have been investigated. A combination of the substrate temperature and the deposition rate determines whether the film grows along the a, c or multiple axes. At low substrate temperatures and low deposition rates, the films grow preferentially along the a-axis. In contrast, higher substrate temperatures and high deposition rates favor c-axis oriented film growth with some admixture of (220). The X-ray diffraction peaks were monitored in real time revealing that both a-axis and c-axis oriented grains nucleated on the surface of the (100) SrTiO3between 6250 and 7650C, although the volume fraction of each orientation was temperature dependent. The structural quality of the a-axis films is superior to that of the c-axis films. The best a-axis films (deposited at 6850C), had a rocking curve width of 0.080, which is 10 times smaller than that for the c-axis films (deposited at 8000C). We have observed a shift of the (007) and (200) peak positions during deposition. The shift in the (007) peak is larger than that for the (200) peak. Defects in the c-axis films were observed, not only at the interface between the film and the substrate, but also on the upper surface of the (final) film; the latter seems to be inherent and is more severe in our films.