Chromium in silicon carbide: electron paramagnetic resonance studies
We report electron paramagnetic resonance measurements for various charge states of chromium substituting for silicon in single crystal epitaxial layers of 6H-SiC. The EPR spectra of Cr3+(3d3) with S=3/2 in the A--state on three lattice sites (a hexagonal and two quasi-cubic ones) were observed. The hyperfine structure of the isotope 53Cr and the superhyperfine structure of the ligand 29Si and 13C were measured. For the neutral A0-state of Cr4+(3d2), a spin triplet EPR spectrum was found with the fine structure parameter D=3.35 GHz and g/sub ///=2.0, gperpendicular to =2.01. Additional anisotropic EPR lines were detected and described by the effective spin 1/2 and g-factors 1.77 and 3.7 when the magnetic field was applied parallel and perpendicular to the c-axis, respectively. In p-type epitaxial layers produced by boron diffusion into chromium-doped samples, new EPR spectra were observed with parameters close to the ODMR data for deep boron centres.