Focused ion beam induced swelling in MgO(001

The interplay between swelling and milling phenomena in determining the morphology of Focused Ion Beam (FIB)-processed MgO(001) was investigated by atomic force microscopy. At the early stages of ion irradiation.. before millinig erosion-is observed, MgO shows a relevant swelling behaviour with protrusion of the bombarded areas up to 6 nm for a dose of 5 x 10(16) ions cm(-2). The effect is mainly ascribed to subsurface defect accumulation, while the low Ga ions concentration, as measured by in-depth Auger analysis, seems to exclude a contribution from ion implantation. In order to explain and control the morphology of Fe/NiO FIB patterned sub-micron structures on MgO substrates, we have also investigated FIB effects on Fe(001) and NiO(001) single crystals. Absent or negligible swelling has been observed on these materials. (c) 2006 Elsevier B.V. All rights reserved.