Optically detected magnetic resonance studies of non-radiative recombination centres in 6H SiC

In n-type 6H SIC substrates and epitaxial layers grown by chemical vapour deposition, several paramagnetic defects were revealed and studied by optically detected magnetic resonance (ODMR). All these defects have an electron spin S=1. Two of these have trigonal symmetry with the symmetry axis along the c-axis of the hexagonal crystal and with the g-values close to 2 (g(parallel to)=2.0034, g(perpendicular to)=2.0080, and g(parallel to)=2.0035, g(perpendicular to)=2.0084). For the other two centres, the angle between the symmetry axis (the z axis) and the c-axis is 71 degrees, with the principal g-values: g(z)=2.0055, g(x)=g(y)=2.0085 and g(z)=2.0060, g(x)=g(y)=2.0095. The fine structure parameters D of all these centres are in the range 1.24-1.35 GHz. From spectral dependence studies of the ODMR signal, all these spectra are shown to be related to non-radiative defects.