The level position of a deep intrinsic defect in 4H-SiC studied by photoinduced electron paramagnetic resonance

Photoinduced electron paramagnetic resonance studies performed on nominally semi-insulating, high purity 4H-SiC have revealed charge transfer from an intrinsic defect (ID) to both the shallow boron acceptor and nitrogen donor. At 4 K, incident photon energy between 1.0 and 1.7 eV produces an increase in paramagnetic boron of approximately the same magnitude as the decrease in the paramagnetic defect concentration. For T<80 K, both spectra remain unchanged after removing the light. Illumination with energy greater than 1.8 eV at 4 K increases the nitrogen, boron, and ID spectra simultaneously, but after blocking the light all three signals return to the pre-illumination level. A model based on excitation to and from the bandedges places the defect level 1.1±0.2 eV above the valence bandedge.