Abstract:
Electrical isolation of n-type GaN epilayers bombarded with MeV light ions is studied by energy
dispersive x-ray spectrometry (EDS). We show that the maximum bremsstrahlung x-ray energy (the
Duane–Hunt limit) can be used to monitor the isolation process in GaN. This method allows the
dose region above the threshold dose for isolation to be conveniently studied, whereas the
application of conventional (low-voltage) electrical techniques in this dose range with large sheet
resistances of the material ()1011 V/sq) is often impossible due to comparable parasitic
resistances of the experimental setup. A correlation of EDS and resistance measurements of GaN
strongly suggests that the magnitude of sample charging scales with the number of
ion-beam-produced deep electron traps which are empty at equilibrium. The results presented
demonstrate the utility of EDS as a powerful and simple technique to study electrical isolation in
wide band-gap semiconductors.
