Growth mechanism of biaxially textured YSZ films deposited by ion-beam-assisted deposition

Biaxially textured YSZ films have a large technical relevance for power or electronic applications of I-ITS films. The YSZ serves as a diffusion barrier and as a template for an epitaxial growth of the I-ITS. On polycrystalline substrates the biaxial alignment is achieved by using an ion-beam-assisted deposition method. The best obtained textures were characterized by a full width at half maximum of 7 degrees in an [111] x-ray diffraction Phi scan. The FWHM decreases with increasing film thickness. The growth mechanism is investigated with respect to three important effects: nucleation, growth selection, and homoepitaxial growth. It could be shown that during nucleation at the beginning of deposition the angle between the assisting beam and the substrate normal has to be fixed at 55 degrees, whereas during the growth selection this angle can be varied. Especially the homoepitaxial effects allow changes in the deposition conditions without destroying the already achieved texture quality.