The growth kinetics of garnet liquid phase epitaxy using horizontal dipping

Abstract

The system for the growth of rare-earth iron garnets from a supersaturated flux is treated as a three-component system: solvent (PbO and B 2O 3), and solvated iron and rare-earth (or yttrium). It is assumed that the different components are solvated separately and that the solubility of garnet can be described with a solubility product. The enthalpy of solution appears to be about 86 kcal mol -1. The model given by Ghez and Giess to describe the kinetics of this process is improved by using a different definition of supersaturation. It is shown that the interface kinetics are first order at high supercooling and become of higher order for low supercooling. The rate-determining steps in the process are both the diffusion through the boundary layer and the incorporation in the solid phase of the rare-earth species. At high growth temperature the process is diffusion-limited whereas at lower temperatures the interface process becomes slowest. With this scheme several phenomena are discussed and it is argued that the diffusion coefficient must be of the order of 10 -6 cm 2 sec -1.