Inelastic X-ray scattering from 6H-SiC

The authors have studied electronic excitations in 6H-SiC using inelastic x-ray scattering. Inelastic scattering spectra were measured at momentum transfers ranging from 0.47 {angstrom}{sup {minus}1} to 2.00 {angstrom}{sup {minus}1} along the c-axis in the hexagonal lattice, i.e. , along [00{center_dot}1], and from 0.67 {angstrom}{sup {minus}1} to 2.00 {angstrom}{sup {minus}1} along the a-axis, i.e., alone, [10{center_dot}0]. Comparison of the two sets of data reveals an orientation dependence of the spectra, except for a characteristic peak at 22--23 eV that occurs for both directions at low Q. This peak has also been observed in electron energy loss spectroscopy studies and is identified as a bulk plasmon. The orientation dependence of the other spectral features is indicative of band structure effects. These data were obtained using a Ge(444) analyzer in a near backscattering geometry.