High thermoelectric performance in two dimensional chalcogenides systems: GaSe and GaTe

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Two-dimensional (2D) group-III chalcogenides like GaSe and GaTe are promising materials for thermoelectric applications.
• Previous theoretical studies on their thermoelectric properties have yielded conflicting results, necessitating further investigation.

Purpose of the Study:

• To systematically investigate the temperature and carrier concentration dependent thermoelectric properties of 2D GaSe and GaTe.
• To identify the material with superior thermoelectric performance for potential device applications.

Main Methods:

• Theoretical investigation of electronic band structure, including band gaps (GaSe: 2.94 eV, GaTe: 1.88 eV).
• Analysis of Seebeck coefficients, carrier relaxation times, and electrical conductivity.
• Calculation of the thermoelectric figure of merit (ZT) as a function of temperature and carrier concentration.

Main Results:

• Both 2D GaSe and GaTe exhibit comparable Seebeck coefficients.
• P-type GaTe demonstrates the longest carrier relaxation time and highest electrical conductivity to thermal conductivity ratio.
• P-type GaTe achieves a high thermoelectric figure of merit (ZT) of 0.91, with performance variation of only ~7% across 300-700 K and 10^11-10^13 holes cm^-2.

Conclusions:

• P-type GaTe possesses outstanding thermoelectric properties, making it a strong candidate for thermoelectric device applications.
• Accurate thermoelectric property assessment requires consideration of carrier relaxation time and spin-orbit coupling effects.
• The stability of p-type GaTe's performance across a broad range of conditions highlights its practical potential.