Interface analysis of high insulating garnet materials using secondary ion mass spectrometry

Abstract

AbstractIn this study, secondary ion mass spectrometry (SIMS) has been used to investigate the interface inhomogeneities of several μm thick layers of magnetic garnets grown on non‐magnetic garnet substrates. The epitaxial layers have the general composition Y3−x−zLaxPbzFe5−y Gay O12, whereas the substrate consists of Gd3Ga5O12. Bombardment of an insulator causes the sample to become charged, leading to loss of the secondary ion signal. This charge has to be compensated for by a simultaneous bombardment of the sample surface with electrons. The dependence of the Pb content (208Pb+) at the film‐substrate interface has been investigated as a function of the dipping parameters and the lattice mismatch. Layers are grown onto films with identical melt compositions but with different supercoolings. In all cases an enhanced Pb concentration at the beginning of the film growth process was found. With a specially grown inhomogeneous sample we were able to show the direct substitution of Pb and Y. The investigation of Ga within the transient layer is particularly difficult because of the high amount of this element in the substrate. The calibration of the count rate scale into formula units has been achieved by electron probe microanalysis (EPMA).