X-ray study of gadolinium gallium garnet epitaxial layers containing divalent Co ions

Structural perfection of gadolinium gallium garnet (GGG; Gd3Ga5O12) epitaxial layers with incorporated divalent Co ions has been studied by means of high resolution X-ray diffraction, X-ray topography, transmission electron microscopy and optical spectroscopy. Epitaxial layers were grown by liquid phase epitaxy from super-cooled high temperature solution with different concentration of Co3O4 and GeO2 on both sides of the polished < 111> oriented GGG substrates. In order to facilitate incorporation of Co2+ ions into the garnet lattice optically inert Ge4+ ions have to be introduced first. High structural perfection is a prerequisite to obtain absorption spectra required for the use GGG epitaxial layers as tunable infrared absorbers.