Comparison of calculated optical response in cubic and hexagonal II-VI semiconductors

We calculate the dielectric function and the second-harmonic generation susceptibility of the II-VI semiconductors in both the cubic and hexagonal phases. These results are based on a. first-principles electronic structure calculation using the full-potential linearized augmented plane-wave method. A comparison is made between the two phases of the linear and second-order optical response for these semiconductors by examining this response in identical coordinate reference frames. Our calculations indicate that there is little difference in the linear optical response between the two phases of the given material below the band gap, but significant differences above the band gap. For the second-order optical response there are significant differences between the two phases of the II-VI semiconductors in both the real and imaginary parts of this susceptibility. The physics of this behavior is discussed. [S0163-1829(98)07035-0].