On the interfacial processes at garnet LPE experiments

LPE experiments are carried out by the horizontal dipping technique with axial rotation of plane Gd3Ga5O12 (GGG) substrates oriented by means of an optical two-circle reflection goniometer. The measured growth rate of (YSm)3(FeGa)5O12 films as a function of the misorientation with respect to a singular (110) plane in the range 0.050 <= α lower than approximately 130 shows an anisotropy depending nonlinearly on the angle. Surface kinetic coefficients are determined by separation of volume transport and interfacial processes. For 00 <= α lower than approximately 80 the k(α) dependence is linear with a slope (1.4 +- 0.2) x 10-2 cm/s, for larger misorientations, however, the slope enlarges. The analysis of the experimental results with the combined volume and surface diffusion model from Gilmer, Ghez, Cabrera shows that the mean surface diffusion distance is in the order of the step height and the desolvation process at transition from surface to a kink can be neglected against the desolvation at transition from the liquid phase to the surface. This corresponds to Chernov's model, where surface diffusion is unimportant. The increasing slope of the k(α) curve for α greater than approximately 80 suggests an interaction and superposition of atomic rough steps. (author)