Researchers from the University of Michigan have synthesized a new class of semiconductor materials on the basis of vishakantaiah alloys of the chalcogenides. The properties of the new compounds allow their use in electronic, optoelectronic, photovoltaic and thermoelectric devices. Article scientists published in the journal Chemistry of Materials.

The entropy is a quantity that characterizes the degree of disorder in the system. Materials with a stable entropy can, in spite of the large enthalpy of mixing, crystallizing in the form of a single crystal. The authors of a new study have suggested that this property of these materials can be used to overcome the problem of synthesis of some semiconductors, which tend to crystallize into more stable compounds.

In the first phase, researchers conducted a computer simulation based on thermodynamic principles and showed that a large configuration entropy as anionic and cationic sublattices chalcogenide alloy GeSnPbSSeTe it stabilizes the single-phase crystal lattice of sodium chloride. Despite the fact that these solid solutions are metastable at room temperature, their condition can be “fixed”, if abruptly cooled from the synthesis temperature to room.

In the second stage, researchers tested the prediction of the model, synthesizing equimolar composition Ge1/3Sn1/3Pb1/3S1/3Se1/3Te1/3 two-stage solid-phase reaction, followed by rapid cooling with liquid nitrogen. X-ray phase analysis of the obtained material showed that it has clear peaks that are due to restructuring of the crystal lattice in the structure of sodium chloride.

The researchers also found that their synthesized semiconductor possesses interesting physical properties: band gap of 0.86 eV at the negative Seebeck coefficient and low thermal conductivity which is almost independent of temperature. These properties make the new class of promising semiconductor for use in electronic, optoelectronic, photovoltaic and thermoelectric devices.