ZNGEP2 CRYSTALS FOR INFRARED-LASER RADIATION FREQUENCY-CONVERSION

In this paper, we present some recent results on integrated studies co ncerned with different aspects of ZnGeP2 crystal technology: synthesis , growth, and post-growth treatment. High-yield two-temperature synthe sis and subsequent growth of ZnGeP2 crystals are considered. By X-Ray phase analysis it has been found that two-temperature synthesis of ZnG eP2 is realized through binary zinc and germanium phosphides formed at the Zn-Ge mixture temperature of about 900 degrees C and the P pressu re of 7 similar to 10 atm. Using the heat-balance equation, a ratio of the thermal conductivity in the solid to that in the liquid ZnGeP2 ne ar the melting point has been determined. The value of the determined ratio is K-l/K-s congruent to 2.3. Analysis of the most favored crysta llographic directions for ZnGeP2 growth has been performed. These dire ctions ale [116], [132], and [102]. Data for optical absorption of the as-grown and the annealed ZnGeP2 crystals are also presented.