Reliable ERD analysis of group-III nitrides despite severe nitrogen depletion

ERD analysis of different group-III nitride films has been performed using a 200 MeV Au beam. Recoil ions were detected employing a gas ionisation detector with large detection solid angle. The nitrogen depletion in the irradiated film volume has been measured as a function of incident ion fluence. Severe depletion rates have been observed for GaN and InN films, resulting in the eventual loss of all nitrogen, with InN losing nitrogen more than ten times faster than GaN. For GaN a delayed onset of the nitrogen depletion is apparent. A two parameter bulk molecular recombination model describes the nitrogen depletion well and enables reliable extrapolations of the original nitrogen content of GaN and InN films. A refinement of the model may be possible by considering the diffusion of nitrogen radicals.