Refractive index for silicon carbide (SiC)

However, previously published values contain errors and do not adequately represent the bulk physical properties of the cubic ({beta}) SiC polytype usually found around carbon stars. We provide new, uncompromised optical constants for {beta}- and {alpha}-SiC derived from single-crystal reflectance spectra and investigate quantitatively (i) whether there is any difference between {alpha}- and {beta}-SiC that can be seen in infrared (IR) spectra and optical functions and (ii) whether weak features from {lambda}~12.5-13.0{mu}m need to be fitted.

We measured mid- and far-IR reflectance spectra for two samples of 3C ({beta}-)SiC and four samples of 6H ({alpha}-)SiC. For the latter group, we acquired polarized data (E{perpendicular.to}c, E{parallel.to}c orientations). We calculated the real and imaginary parts of the complex refractive index (n({lambda})+ik({lambda})) and the ideal absorption coefficients via classical dispersion fits to our reflectance spectra.