Highly (00l)-oriented Bi₂Te₃/Te heterostructure thin films with enhanced power factor

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Nanoscale heterostructure interfaces enhance thermoelectric performance via energy-dependent carrier filtering.
• Optimizing thermoelectric materials requires precise control over microstructure and interfaces.

Purpose of the Study:

• To fabricate highly (00l)-oriented Bismuth Telluride/Tellurium (Bi2Te3/Te) heterostructure thin films.
• To investigate the thermoelectric properties of these heterostructures.
• To understand the role of interfaces in optimizing thermoelectric performance.

Main Methods:

• Fabrication of Bi2Te3/Te heterostructure thin films using magnetron co-sputtering.
• Growth on single-crystal Magnesium Oxide (MgO) substrates for preferred orientation.
• Characterization of thermoelectric properties, including Seebeck coefficient and electrical conductivity.

Main Results:

• Optimized thermoelectric performance achieved in Bi2Te3/Te heterostructures with 63.8 at% Tellurium content.
• High Seebeck coefficient of -157.7 μV K⁻¹ and electrical conductivity of 9.72 × 10⁴ S m⁻¹ were recorded.
• A high power factor approaching 25 μW cm⁻² K⁻² was obtained, attributed to interfacial filtering and preferred orientation.

Conclusions:

• Bi2Te3/Te heterostructure interfaces effectively filter carriers, enhancing the Seebeck coefficient.
• Highly preferred (00l) orientation facilitates carrier transport in the a-b plane, boosting electrical conductivity.
• Microstructure design and regulation offer a promising strategy for developing high-performance thermoelectric materials.