ZNGEP2 SYNTHESIS AND GROWTH FROM MELT

The two-temperature technique has been examined for ZnGeP2 synthesis. The effect of the cold zone temperature on the Zn diffusion and the Zn P2 formation outside the ternary compound reaction zone has been studi ed. A qualitative analysis of the Zn diffusion equation taking into ac count the P mass transport has allowed us to identify conditions where no Zn diffusion is observed. The effect of the ampoule surroundings o n the ZnGeP2 crystal growth has been investigated for the vertical Bri dgman and vertical gradient freezing methods. The steady-state thermal conductivity equation has been solved for different ampoule surroundi ngs. The proposed numerical model has established the reasons for the polycrystalline structure and physical properties heterogeneity of ZnC eP2 crystals, viz. the isotherm concavity and variable growth rate wit h respect to the ampoule translation speed. (C) 1997 Elsevier Science S.A.