The theoretical refractive index of the direct-gap II–VI compounds CdSe, CdS, and CdSexS1–x with the wurtzite lattice structure is calculated for frequencies below the fundamental absorption edge. Use is made of the band structure of the Kane theory, modified to include the dependence of the refractive index on the effective hole masses of the three valence bands, the lattice constants a(Å) and C(Å) of the hexagonal structure, and the direction of polarization of the incident wave. An extension of the previous result for the refractive index of a cubic zinc blende crystal, in which birefringence is absent, to the hexagonal wurtzite structure, where birefringence occurs, is given. Results are obtained for the refractive indices of the ordinary and extraordinary rays in terms of experimentally available quantities, which include the direct-band-gap energy G, the effective electron mass mn, the three effective hole masses mp1,mp2, and mp3 of the three valence bands at k = 0, and lattice constants a(Å) and C(Å). Numerical values of the refractive index for values of x in the range 0 ≤ x ≤ 1 are given and compared with experimental results.
© 1986 Optical Society of AmericaPDF Article