Prediction of α-phase GeSn solid solution under pressure

Abstract

The compression effect on the phase diagrams of the GeSn and SiSn systems is investigated using the electronic theory based on pseudopotentials and the virtual crystal approximation for the disordered alloy. The hypothetical solid solution for the GeSn and SiSn systems undergoes a pressure-induced phase transition from the α-phase of substitutional diamond-type to β-phase of disordered white-tin-type. The heat of solution ΔE( χ, P) for Ge 1− x Sn x and Si 1− x Sn x systems under pressure P is large for the Sn-rich region and decreases as the crystal is compressed. Consequently, we predict the appearance of an α-phase solid solution for the GeSn system under pressure. The phase diagrams under pressure are obtained quantitatively. Because of the large heat of solution, the solid solution for the SiSn system is not formed under pressure.