CHROMIUM IN SILICON-CARBIDE - ELECTRON-PARAMAGNETIC-RESONANCE STUDIES

We report electron paramagnetic resopance 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 Cr-53 and the superhyperfine structure of the ligand Si-29 and C-13 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(parallel-to) = 2.0, g(perpendicular-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.