Nitrogen Implantation in SiC: Lattice Disorder and Foreign-Atom Location Studies

The implantation behaviour of 25–80 keV nitrogen in α-SiC has been investigated for doses of 2 × 1015and 2 × 1016 N atoms/ cm2 as a function of implantation temperature (20–450°C) and subsequent anneal treatments up to 1485°C. Backscattering yield measurements (using a 2 MeV helium beam) and 15N(p, a) nuclear reaction yield measurements (using a 1 MeV proton beam) have been used to study the amount of residual damage in the crystal and the lattice location of the implanted nitrogen atoms, respectively. The results clearly indicate the advantage of high temperature implantation in producing a high “substitutional” fraction (~ 70%) and a minimum damage level. In the 450° C implants, a maximum substitutional nitrogen concentration of ~ 1 × 1021/cm3 was obtained. Evidence for an anomalous “inverse annealing” stage at ~ 800°C is observed for the 350 and 450° C implants, with the residual damage level increasing markedly and the “substitutional” nitrogen fraction decreasing to around the 50% level.