Structural, elastic, and thermodynamic properties of ZnSexTe1−x: A first-principles study

The structural, elastic, and thermodynamic properties, as well as optical bowing parameters of ZnSexTe1−x ternary alloys are investigated. We adopt the Landau–Lifshitz structural models using the first-principles method, and show that alloys of different structures but identical compositions exhibit highly similar parameters. Results also reveal that the structural relaxation effect plays a crucial role in the gap bowing parameter. The different constituents of the alloys are all mechanically stable. However, they exhibit phase separation at low temperatures because of thermodynamic reasons. The calculated phase diagram shows the temperature at which a stable alloy may be formed for the different compositions of Se. It also demonstrates that the lowest temperature indicating the thermodynamic stability of alloys over the whole composition range (the critical temperature) is about 757 K.

► The physical origins of the gap bowing parameter in ZnSexTe1−x alloys are demonstrated clarify.
► We conclude that the different constituents of alloys are mechanically stable by elastic constants.
► The mixing enthalpy theory shows that ZnSexTe1−x alloys undergo phase separation, at low temperatures.
► The phase diagram of ZnSexTe1−x can know the conditions at which the alloys are stable.