Si‐Ge‐Metal Ternary Phase Diagram Calculations

Solution crystal growth and doping conditions of Si-Ge alloys used for high-temperature thermoelectric generation are determined here. Liquid-phase epitaxy (LPE) has been successfully employed recently to obtain single-crystalline ho-mogeneous layers of Si-Ge solid solutions from a liquid metal solvent. Knowledge of Si-Ge-metallic solvent ernary phase diagrams is essential for further single-crystal growth development. Consequently, a thermodynamic equil ibrium model was used to calculate the phase diagrams of the Si-Ge-M systems, including solid solubilities, where M is A1, Ga, In, Sn, Pb, Sb, or Bi. Good agreement between calculated liquidus and solidus data and experimental DTA and microprobe re-sults was obtained. The results are used to compare the suitability of the different systems for crystal growth (by LPE-type process). The solid solutions between Si and Ge have been of par-ticular interest since their discovery and publication of the phase diagram in 1939 (1). Si-Ge alloy-based high-tempera-ture thermoelectrics are usually prepared by hot-pressing. However, because of material inhomogeneity and grain boundaries, it is difficult o satisfactorily relate the thermal

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