Phase equilibria were established in the InRhAs system at 600 °C, using X-ray diffraction, electron probe microanalysis, scanning electron microscopy and differential thermal analysis. InAs was demonstrated to be in thermodynamic equilibrium with RhIn3, Rh3In5As2, RhAs2 and RhAs3. The phase Rh3In5As2, which has not been reported previously in the literature, was found to possess the cubic Ir3Ge7 (cI40, D8f) structure, with the lattice parameter α=0.91653±6 nm. A combination of X-ray diffraction and differential thermal analysis experiments indicated that Rh3In5As2 forms peritectically at 829±5 °C, according to the reaction: RhIn+L→Rh3In5As2. A schematic 50 at.% indium InRhAs phase diagram isopleth was proposed to illustrate this reaction. RhAs was found to dissolve 8 at.% indium. Rh9+xAs7 RhIn3 and RhIn also showed some ternary solubility. RhIn exhibited an appreciable range of binary homogeneity, extending from at least 44-49 at.% rhodium at 600 °C. The results of the present investigation suggest that RhIn3 would be most suitable as a thermodynamically stable, rhodium-based contact to InAs.
- Differential thermal analysis
- Electron probe microanalysis
- Phase equilibria
- Scanning electron microscopy
- X-ray diffraction