Crystallinity of Ce Substituted YIG Films Prepared by RF Sputtering

Abstract

The crystallinity of Ce-substituted yttrium iron garnet ( Ce1\\colonYIG) film was studied by measuring X-ray diffraction (XRD) and deformation and by transmission electron microscope (TEM) observation. The Ce1\\colonYIG films were prepared on anisotropic etched or unetched GGG and cation doped GGG (GCGMZG) substrates by RF sputtering. They have a narrow crystallization region as regards substrate temperature and this region becomes narrower as the O2 gas flow rate is increased. The XRD measurements and TEM observation revealed that crystallized Ce1\\colonYIG films have a multilayered structure except for those on GCGMZG substrates. Their layered structure was dependent on their thickness, the substrate treatment, the lattice constant difference between the film and the substrate and the O2 flow rate. They also exhibited compressive deformation which originated mainly from the lattice constant difference between the film and the substrate. The crystal growth mechanism of Ce1\\colonYIG films was considered on the basis of recent work on the growth mechanism of compressively deformed strained semiconductor film.