Thermodynamic Analysis and Single Crystal Growth of ZnSe from ZnSe-N-H-Cl System

The thermodynamic properties of the transporting reactions in the closed-tube ZnSe-N-H-Cl system are analyzed by solving a set of equations with numerical methods, where NH 4 Cl serves as the transport agent. The results show that ZnSe-NH 4 Cl system has the properties of high total pressure and low transporting reaction equilibrium constant. The decomposition of hydrogen selenide determines the difference between the partial pressures of ZnCl 2 and H 2 Se, which slows down the growth rate. This difference can be adjusted by adding extra Se and the hydrogen (H 2 ) produced through decomposition of NH 3 . The ZnCl 2 and a little extra Se should be added into the ZnSe-NH 4 Cl system to improve the utilizing efficiency of H 2 and the concentration of practical transporting components of ZnCl 2 and H 2 Se. A ZnSe single crystal as large as 20 x 15 x 8 mm 3 was obtained by using ZnCl 2 ·2NH 4 Cl as the transport agent with a little extra Se at about 1300 K. The experimental results about the diffusion-limited transport rate are well coincided to the thermodynamical analysis.