EFFECT OF ION FLUENCE ON THE SURFACE-MORPHOLOGY OF SINGLE-CRYSTAL MAGNESIUM-OXIDE IMPLANTED WITH XENON

The surface morphology (001)-oriented single-crystal magnesium oxide ( MgO) implanted with xenon ions has been examined using atomic force mi croscopy. It was found that at the lowest fluence used in this study ( 1.0 x 10(14)/cm(2)), a slight roughening of the (001) surface occurred . The magnitude of this roughening remained fairly constant with incre ases in fluence in the range 1.0 x 10(14)/cm(2) to 3.0 x 10(16)/cm(2). Implantation at fluences of greater than or equal to 1.0 x 10(17)/cm( 2) caused significant surface roughening with the concomitant formatio n of micron-sized blisters. The appearance of some of these blisters r esembles the rosette pattern that is also observed when the cleaved su rfaces of MgO crystals are etched following indentation using a spheri cal indenter. This observation suggests that these blisters are formed by the growth of xenon inclusions, during implantation, by a dislocat ion loop punching mechanism.