Theoretical and electron paramagnetic resonance studies of hyperfine interaction in nitrogen doped 4H and 6H SiC

Motivated by recent experimental findings on the hyperfine signal of nitrogen donor (NC) in 4 H and 6 H SiC, we calculate the hyperfine tensors within the framework of density functional theory. We find that there is negligible hyperfine coupling with 29Si isotopes when NC resides at h site both in 4 H and 6 H SiC. We observe measurable hyperfine coupling to a single 29Si at k site in 4 H SiC and k1 site in 6 H SiC. Our calculations unravel that such 29Si hyperfine coupling does not occur at k2 site in 6 H SiC. Our findings are well corroborated by our new electron paramagnetic resonance studies in nitrogen doped 6 H SiC.