ON THE MICROSCOPIC STRUCTURES OF SHALLOW DONORS IN 6H SIC - STUDIES WITH EPR AND ENDOR

Nitrogen and phosphorus in 6H-SiC were investigated with electron paramagnetic resonance (EPR) at 10 GHz and at 140 GHz and with electron nuclear double resonance (ENDOR). The phosphorus defects were prepared by neutron transmutation of Si-30 in 6H-SiC. We observed two sets of EPR spectra due to two different phosphorus-related defects. Both EPR spectra exhibit a strong temperature dependence. It is proposed, that one of these EPR spectra is due to the isolated shallow phosphorus donor on Si sites and the other due to a P-vacancy-pair defect. The electronic structures of the shallow donors P and N are discussed using effective mass theory. It is shown that the shallow P donor on the hexagonal site has not yet been observed.