Ion Damage and Annealing of Epitaxial Gallium Nitride and Comparison With GaAs/AlGaAs Materials
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Mat. Res. Soc. Symp. Proc. Vol. 395 0 1996 Materials Research Society
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Fig.1
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2MeV He+ ion channeling spectra illustrating the build up of 90 keV Si disorder (LN temperature) in epitaxial GaN on sapphire.
2 remarkably resistant to ion damage even at LN temperatures. A dose of 8.4 x 1014 cmproduces less than a twofold increase in both Xmin and the surface peak area, whereas an order of magnitude lower dose into GaAs [9] would have produced a continuous amorphous layer extending to a depth of about 1200 A. This suggests that dynamic annealing involving annihilation of implant-induced defects is extremely efficient. Indeed, by a dose of 7.2 x 1015 cm- 2 , the ion channeling spectrum still has not reached the random level (complete disordering) even though every lattice atom at the peak of the damage distribution (- 900 A) has been displaced more than 100 times. It is interesting that the damage (when it does accumulate) builds up both at the ion range (arrowed) and at the surface. By a dose of 7.2 x 1015 cm-2 there is little evidence for amorphous material as obtained from TEM. However, when the surface peak reaches the random level the damage extends back into the bulk from the surface at higher doses (e.g. 2.4 x 1016 cm- 2 ). The surface appears to be a strong sink for defects and the results suggest that the surface may eventually be a nucleation site for growth of the amorphous phase, although this has not been confirmed as yet by TEM.
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(--Depth (A) 1000 2000
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Fig.2
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2 MeV He+ ion channeling spectra illustrating the build up of 90 keV Si disorder (LN temperature) in Al 0 .95Ga 0 .05 As on GaAs. Note that a GaAs cap layer of _
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