An Sn-induced resonant level in β-As₂Te₃

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid-State Chemistry

Background:

• Thermoelectric materials are crucial for energy conversion.
• Impurity-induced resonant levels can enhance thermoelectric performance.
• Bismuth telluride (Bi2Te3), lead telluride (PbTe), and tin telluride (SnTe) are known thermoelectric semiconductors.

Purpose of the Study:

• To investigate the effect of tin (Sn) as a resonant impurity in p-type beta-arsenic telluride (β-As2Te3).
• To demonstrate how Sn distorts the electronic density of states and influences thermoelectric properties.
• To explore new strategies for optimizing thermoelectric materials.

Main Methods:

• First-principles calculations to determine electronic band structure.
• Transport property measurements on polycrystalline samples.
• Comparison with theoretical predictions using Boltzmann transport theory (Ioffe-Pisarenko curves).

Main Results:

• Sn acts as a resonant impurity, creating a sharp peak in the electronic density of states near the Fermi level in β-As2Te3.
• Sn significantly enhances the thermopower of β-As2Te3, deviating from theoretical predictions for conventional dopants.
• Gallium (Ga) and Iodine (I) substitutions behaved as expected, following rigid-band-like doping trends.

Conclusions:

• The observed enhancement in thermoelectric performance of β-As2-xSnxTe3 is attributed to the resonant level induced by Sn.
• Inducing resonant states in the electronic band structure is a viable strategy for optimizing β-As2Te3.
• This research opens new pathways for designing advanced thermoelectric materials.