Anisotropy of UV-reflectivity in wurtzite crystals: a comparison between GaN and CdSe

The imaginary parts of the dielectric functions ϵ2(ω) are calculated for wurtzite CdSe and GaN within the one-electron approximation using the linear muffin-tin-orbital method and analyzed in terms of separate band-to-band contributions and critical points. Differences and similarities are pointed out. The effects of excitonic enhancement at critical points are discussed.