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doped ZnO after annealing [11]. Finally Nord et al [12] predicted N segregation in ion implanted GaN with molecular
dynamics calculations while N 2 bubbles formed after 2 and 4.7 MeV Au implantation into GaN are apparent in transmission
electron micrographs [6]. The RL related to the N 2 gaseous bubbles disappears after RTA at 800 o C, as shown in Fig. 1. This
implies that either N 2 outdiffuses from the sample and/or that the N – N bonds dissociate and new Ga-N are formed (even
though the formation of In-N bonds cannot be excluded). In addition to that, annealing also partially restores the
characteristics of the NEXAFS peaks, indicating partial recovery of the implantation induced lattice damage.
In conclusion, implantation of GaN with 700 keV In ions and a fluence of 5x10 15 cm -2 results to the formation of a
200nm – thick surface amorphous layer while the underlying GaN layer is severely defected. Furthermore, implantation
causes the evolution of a sharp resonance line that appears above the N K absorption edge. On the basis of the presented
experimental evidence the RL is attributed to the implantation induced formation of N 2 . Finally, rapid thermal annealing at
800 - 900 o C is insufficient for the complete recovery of the implantation induced lattice damage.
Acknowledgement: The measurements at ELETTRA were financially supported by the “PYTHAGORAS” program of the
Greek Ministry of Education and the ELETTRA user program.
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