Reassignment of phosphorus-related donors in SiC

Combining efficient density-functional based tight-binding molecular dynamics with ab initio calculations, we show that despite higher formation energies the incorporation of phosphorus at the carbon sublattice is favored by kinetic effects during the annealing processes. Based on the calculated hyperfine parameters the shallow P₁,P₂ donors can be attributed to this kind of incorporation (PC or PCCSi) only. The former controversially discussed spectra with small splittings are most probably due to isolated P at the silicon sublattice (PSi). Our theoretical results are supported by new electron paramagnetic resonance measurements additionally presented in this work: in 6H-SiC samples, in situ P-doped during growth, only the so-called P+V spectrum occurs at temperatures between 80.3em0exK and 800.3em0exK, strongly indicating that at least three classes of different phosphorus-related defects are involved.