Electron paramagnetic resonance of scandium in silicon carbide

Abstract

The EPR spectra of scandium acceptors and Sc2+(3d) ions are observed in 6H-SiC crystals containing a scandium impurity. The EPR spectra of scandium acceptors are characterized by comparatively small hyperfine interaction constants, whose values are consistent with the constants for other group III elements in SiC: boron, aluminum, and gallium acceptors. The EPR spectra of scandium acceptors undergo major changes in the temperature interval 20–30 K. In the low-temperature phase the EPR spectra are characterized by orthorhombic symmetry, whereas the high-temperature phase has higher axial symmetry. The EPR spectra observed at temperatures above 35 K and ascribed by the authors to Sc2+(3d) ions, or to the A2− state of scandium, have significantly larger hyperfine structure constants and narrower lines in comparison with the EPR spectra of scandium acceptors. The parameters of these EPR spectra are close to those of Sc2+(3d) in ionic crystals and ZnS, whereas the parameters of the EPR spectra of scandium acceptors correspond more closely to the parameters of holes localized at group III atoms, in particular, at scandium atoms in GeO2. It is concluded that in all centers the scandium atoms occupy silicon sites.