Atomic layer-by-layer thermoelectric conversion in topological insulator bismuth/antimony tellurides

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Efficient thermoelectric materials require controlled electrical and thermal transport.
• Bismuth telluride (Bi2Te3) and antimony telluride (Sb2Te3) are top thermoelectric materials and topological insulators (TIs).
• Topological insulators exhibit unique electronic properties at thin film interfaces.

Purpose of the Study:

• To explore novel thermoelectric conversion at the atomic monolayer steps of few-layer topological insulating Bi2Te3 and Sb2Te3.
• To investigate the role of quantum effects in thermoelectricity at the nanoscale.

Main Methods:

• Utilized scanning photoinduced thermoelectric current imaging.
• Analyzed thermoelectric conversion at atomic monolayer steps.
• Investigated optothermal motion of charge carriers.

Main Results:

• Demonstrated efficient thermoelectric conversion at atomic steps in Bi2Te3 (n-type) and Sb2Te3 (p-type).
• Showcased optothermal motion of hot electrons and holes through 2D subbands and surface states.
• Confirmed geometrically deterministic thermoelectric conversion.

Conclusions:

• Thermoelectric conversion can be achieved at atomic steps by exploiting the quantum nature of topological insulators.
• This provides a new design principle for compact thermoelectric circuitry at the ultimate size limit.