Surface morphologies and quality of thick liquid phase epitaxial garnet films for magneto-optic devices

Abstract

Surface morphologies of thick Gd : YIG garnet films grown by liquid phase epitaxy (LPE) are found to be classified into three types: “mirror”, “striation” and “swirl”. “Mirror” appears when films are grown at low temperature or when the film thickness is small. “Striation”, which takes over the striation of the substrates, appears when the growth temperature or film thickness is medium. “Swirl” appears when the growth temperature is high or the film thickness is large. When “swirl” takes place, flux is included into the thick films. A mechanism for the morphological change with increase in film thickness is shown. An increase in half-width of the X-ray rocking curve with an increase in film thickness is found for the {111} films. This can be attributed to the generation of {110} and {211} facets which have larger lattice constants than the {111} and to crystallinity degradation due to flux inclusion. The {110} or the slightly misoriented {110} substrate is recommended to be employed so as to obtain inclusion-free thick films.