The effect of 5.4MeV He-ion bombardment of n-type material at 25K was studied. It was found that the mobility and carrier concentration were reduced. It was recalled that deep-level transient spectroscopic measurements had shown that electrically active defects were introduced during such bombardment. In an attempt to remove the defects and return the material to its original state, it was subjected to isochronal annealing at temperatures of up to 443K. Very little recovery was observed, and it was concluded that the defects which caused the degradation of the mobility and carrier concentration were thermally stable up to 443K. There was very little change in the peak mobility temperature as a function of the incident He-ion fluence.

Electrical Characterization of Low Temperature He Ion-Irradiated GaN. M.Hayes, S.A.Goodman, F.D.Auret: Nuclear Instruments and Methods in Physics Research B, 1999, 148[1-4], 437-40