Nitrogen Donor Aggregation in 4H-SiC: g-Tensor Calculations
The microscopic origin of the Nx EPR-lines observed in heavily nitrogen doped 4H-SiC and 6H-SiC is discussed with the help of EPR parameters calculated from first principles. Based on the symmetry of the g-tensors we propose a model with distant NC donor pairs on inequivalent lattice sites which are coupled to S=1 centers but with nearly vanishing zero-field splittings, giving rise to an essentially S=1/2 like spectrum. The proposed aggregation in neutral donor pairs can contribute to the saturation of the free concentration observed in heavily nitrogen doped SiC.
N. Wright, C.M. Johnson, K. Vassilevski, I. Nikitina and A. Horsfall
U. Gerstmann et al., "Nitrogen Donor Aggregation in 4H-SiC: g-Tensor Calculations", Materials Science Forum, Vols. 556-557, pp. 391-394, 2007