Electrical characterization of low temperature He-ion irradiated GaN

In this paper, we report on the modification of the mobility and carrier co ncentration due to low temperature (25 K) 5.4 MeV He-ion irradiation of n-t ype GaN. Both the mobility and the carrier concentration were reduced as a result of the incident high energy He-ions. It is known from DLTS measureme nts that electrically active defects are introduced during such an irradiat ion process. In an attempt to thermally remove the defects in order to see if the material recovered to its original specifications, it was subjected to isochronal annealing up to 443 K. We observed very little recovery, lead ing us to conclude that the defects causing the degradation of the mobility and carrier concentration are thermally stable up to the anneal temperatur es used here. There was very little change in the peak mobility temperature as a function of incident He-ion fluence. (C) 1999 Elsevier Science B.V. A ll rights reserved.