Electron paramagnetic resonance of erbium in bulk silicon carbide crystals

We report the first EPR observation of rare-earth impurities in erbium doped bulk 6H-SiC crystals, grown by the sublimation sandwich-method. Two lines for axial Er3+ centre with crystalline c-axis being the axis of the g tensor, which seem to arise from different lattice sites in 6H-SiC and three Er3+ centres with same nearly orthorhombic symmetries, attributed to different lattice sites have been observed. A direct identification of erbium ions has been established by the presence of hyperfine interaction with Er-167 nuclei. The principal g values of the axial and orthorhombic Er3+ centres were found. The average g values suggest that the parent cubic ground state may have Gamma(7) representation for both centres. Presumably, erbium substitute for silicon in a regular environment for axial centre. The orthorhombic Er3+ seems to include another defect at carbon position along with Er3+ ion at silicon site. The EPR spectrum of the excited state of Er3+ in 6H-SiC seems to be observed at higher temperature. The trace amounts of the other rare-earth elements, in particular Dy3+, had probably been present in EPR spectra. (C) 1997 Published by Elsevier Science Ltd.