Thermodynamics and kinetics of in situ synthesized In-P melt by the phosphorus injection and its solidification behavior

Abstract

In the study, the thermodynamics and kinetics of phosphorus injected into indium melt has been investigated. The partial pressures of the phosphorus gases, P(g), P2(g) and P4(g), in equilibrium with the In-P melt with different concentrations is calculated from 1345 to 1700 K. Based on the thermodynamic analysis, the kinetic process of phosphorus injection synthesis has been studied in details, which involves the relationship among the absorption rate, synthesis efficiency, bubble diameter, rising distance of bubble, bubbling rate, injection rate, environmental pressure and melt concentration. The calculated absorption rate is in good agreement with the experimental data. Based on the kinetic analysis, 20 kg InP polycrystals are synthesized in 3 h by optimizing the synthesis parameters. It is found that local indium and phosphorus separation occurs near the bottom of the ingot during solidification from the P-rich melt. The phosphorus depositions present the radioactivity round rod, columnar polyhedron and fibrous characteristics. The formation mechanism of the separation phenomenon is analyzed. Finally, the methods of obtaining stoichiometric and P-rich polycrystals are put forward.