Effects of implantation defects on the carrier concentration of 6H-SiC

The effects of ion irradiation defects on the carrier concentration of 6H-SiC epitaxial layer were studied by current-voltage (I-V), capacitance.-voltage (C-V) measurements, thermally stimulated capacitance and deep level transient spectroscopy. The defects were produced by irradiation with 10 MeV C+ at a fluence of 10(11) ions/cm(2) supercript stop and subsequent thermal annealings were carried out in the temperature range 500-1700 K under N-2 flux. I-V and C-V measurements reveal the presence of a high defect concentration after irradiation and annealing at temperature lower than 1000 K. Thermally stimulated capacitance measurements show that some of the defects induce a deactivation of the nitrogen donor, while some of the generated defects, behaving as donor-like traps, contribute to increase the material free carrier concentration at temperatures above their freezing point. Deep level transient spectroscopy measurements performed in the temperature range 150-450 K show the presence of several overlapping traps after ion irradiation and annealing at 1000 K: these traps suffer a recovery and a transformation at higher temperatures. The annealing of all traps at temperatures as high as 1700 K allows one to completely restore the n-type conductivity. The defects mainly responsible of the observed change in the carrier concentration are identified.