Characterization of microstructure in ion-implanted garnet by transmission electron microscopy

Microstructural changes induced by ion implantation in films of (SmYGdTm)3Ga0.4Fe4.6O12garnet have been investigated by transmission electron microscopy incorporating a special cross-sectioning technique. These films were produced by liquid phase epitaxy on {111} garnet substrates and subsequently implanted with ions of deuterium at 60 keV and doses ranging from 1.0 to 4.5 × 10¹⁶D+2/cm²and ions of oxygen at 110 and 180 keV and doses ranging from 1.0 to 8.6 × 10¹⁴O+/cm². Implantation with deuterium produces a single band terminating at about 450 nm below the implanted surface implantation with oxygen produces amorphization of a surface layer, whereas implantation with both deuterium and oxygen enchances the width of this layer, all of which correlate well with estimates of projected range. The amorphization evolves in three separate stages: First, an implantation band, delineated by the induced strain profile, is formed; then isolated amorphous particles appear; finally, these particles merge into a continuous band. The critical implantation dose for this last stage is about 5.7 × 10¹⁴O+/cm². Relationships between such structural changes and magnetic properties are also considered.