The constant-strain electro-optic coefficients and dielectric constants of two ternary semiconductors (CuGa${\mathrm{S}}_2$ and ZnGe${\mathrm{P}}_2$) with the chalcopyrite structure have been measured. The magnitudes of the coefficients are similar to those of the binary analogs (ZnS and GaP). However, the signs of the CuGa${\mathrm{S}}_2$ coefficients appear to be positive whereas the ZnS coefficient is negative. The ZnGe${\mathrm{P}}_2$ coefficients are found to have opposite signs to each other.

• Received 16 July 1973

DOI:https://doi.org/10.1103/PhysRevB.9.558