W. Tolksdorf

Controlled lattice constant mismatch by compositional changes in liquid phase epitaxially grown single crystal films of rare earth yttrium iron gallium garnets on gadolinium gallium garnet substrates

Abstract Liquid phase epitaxy (LPE) by dipping substrates into supercooled fluxed solution provides a convenient way of changing the melt and film composition. The apparatus, method and composition of the melts that we use will be described in detail. The composition of the layer is essentially Y 3 GaFe 4 O 12 , which has a smaller lattice constant than the Czochralski-grown gadolinium gallium garnet substrate. By substitutions such as gadolinium, samarium or lanthanum for yttrium the lattice constant mismatch can be controlled. The effect of these substitutions on film properties such as cracks, stresses and magnetic domain pattern as well as the interaction of substrate defects such as dislocations with the epitaxially-grown film are discussed.

Growth mechanisms and composition in the LPE process for bubble domain materials

A review is presented of some recent results obtained in the LPE growth of magnetic garnet thin films for bubble domain applications by means of vertical dipping and without rotation of the substrate, in a PbO and B 2 O 3 flux. The design of a furnace in which films of the composition Y 3− x La x Fe 5− y Ga y O 12 have been grown reproducibly is described. The homogeneity of the composition of the layers is discussed with respect to film thickness. A clear relation has been found between changes in the lead content and the growth rate for films of Y 3 Fe 5 O 12 . The stoichiometry of these layers is also found to change with lead incorporation, depending on the position of the LPE melt in the phase diagram. Studies of the growth kinetics of Y 3 Fe 5 O 12 films as a function of supercooling, growth temperature and lattice misfit have shown the existence of a transient period of 5–10 min during which the compositional variations take place.

LPE growth of bismuth substituted gadolinium iron garnet layers: Systematization of experimental results

Abstract Experimental data concerning the solubility behaviour of bismuth, aluminium, gallium substituted gadolinium iron garnet in lead oxide/bismuth oxide based melts as well as the segregation behaviour of the substituents are systematized with the aid of available theoretical models.

The effect of local cooling and accelerated crucible rotation on the quality of garnet crystals

Abstract To characterize growth and properties of yttrium iron garnet single crystals a detailed description of growth conditions is given including temperature distribution in the fluxed melt in terms of isotherms. The influence of local cooling and the accelerated crucible-rotation technique, recently published by Scheel and Schulz-DuBois, are described. Growth features on crystal faces are discussed, and analytical data about impurities are summarized.

Growth of yttrium iron garnet single crystals

Abstract An economical method has been developed in which the bottom-grown yttrium iron garnet single crystals are separated from the flux by turning the crucible inside the furnace after the slow cooling period. Special covers on the crucible make it possible to take out the garnet crystals and feed back the corresponding raw materials for the next run. No noticeable flux loss occurs, when using a tightly welded crucible provided with a narrow S-shaped platinum evaporation tube. A seed crystal can be used, the crucible must then be turned twice.

Dependence of lattice parameter on composition in substituted yttrium iron garnet epitaxial layers

Abstract The growth of single crystal layers is described for the composition Y 3− x R x Fe 5− y Ga y O 12 (R=Sm or La) on (111) Gd 3 Ga 5 O 12 substrates by liquid phase epitaxy. The reproducibility of the method is presented, the dependence of the distribution coefficients of the substituents on supercooling, and the relation between strain and composition of the layers are discussed. It is concluded that the formation or ordering of vacancies or interstitials, or substitution by impurities such as Pb 2+ of B 3+ , have a negligible effect on the lattice constant.

Facet formation of yttrium iron garnet layers grown epitaxially on spheres

Abstract The formation of facets of yttrium iron garnet layers with thicknesses of 1 to 8 μ m was studied by liquid phase epitaxy using polished spheres of gadolinium gallium garnet single crystals of 2 to 8 mm diameter as substrates. The most dominant (largest area) facets were {110} and {211} which frequently exhibited flat, spiral type growth hillocks. {321} facets were always a little bit smaller. {210} and {332} facets were found to be very small and not completely flat. No facets could be observed in the [100] directions but the surfaces of these layers show a quite different texture compared to other directions such as [111]. The sticking of melt droplets to the [100] directions of the sphere proves the preference of wetting for this direction.

Electron probe microanalysis of epitaxial garnet films

The capability of computer controlled wavelength dispersive microprobe instrumentation was tested by application to quantitative analysis of multi-element garnet layers. The depth of X-ray production and influence of substrate were studied on films with thickness ranging from 0.7 to 15 μm. Test analyses of well-defined bulk garnet materials using selected polycrystalline and single crystal calibration standards showed the systematic error not exceed a value of ±0.3 wt% element, bringing it close to the limits imposed by the reproducibility of the measurements. The time required for a non-destructive analysis by automatic data acquisition and on-line matrix correction is about 200 s (9 elements) which is acceptable for routine analysis of large series of samples. This includes the measurement of concentrations <1 wt% with a reproducibility of about 15%.

Growth of magnetic garnet single crystals from high temperature solution

Abstract A review is given to show the development of growth techniques for single crystals for the incongruently melting yttrium iron garnet. As a result of this world-wide development a technique is described in some detail which allows well controlled nucleation and growth using a high temperature solution.

Growth of Yttrium iron garnet multi-layers by liquid phase epitaxy for single mode magneto-optic waveguides

Abstract The growth of multi-layers of substituted yttrium iron garnet on non-magnetic garnet substrates is described. They are used for non-reciprocal symmetric single mode magneto-optic waveguides for communication systems in the wavelength range of 1.3 to 1.6 μm. Core and cladding layers are grown in one dipping process by changing the rotation rate resulting in refractive index differences of 1 X 10 -3 to 10 X 10 -3 . Growth conditions, compositions, lattice mismatch and magneto-optic properties of the layers are described.