Thermodynamics of phase separation in SiGe solid solution and construction of the miscibility gap at low temperatures for cubic-phase Si-Ge binary alloy semiconductors

The subject paper presents a thermodynamic study of the low-temperature spinodal decomposition in SiGe solid solutions and its impact on the properties and performance of Si-Ge alloy semiconductors. The miscibility gap in SiGe alloys originates from their positive enthalpy of mixing and has implications on their bandgap, charge carrier mobility, thermal conductivity and optoelectronic properties. In this study, we have calculated the enthalpy of mixing of Si-Ge alloy system using DFT and based on our results, we were able to construct a low-temperature phase diagram and identify the unstable and metastable regions of the spinodal plot and also identify the different thermodynamic and kinetic factors that govern the formation of these phase-separated regions.