2D Bi₂Te₃/Si heterostructure with high thermoelectric power factor enabled by interface regulated carrier injection

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Optimizing charge carrier concentration in 2D bismuth telluride (Bi₂Te₃) is crucial for advancing thermoelectric performance.
• Existing methods often face limitations in achieving the desired charge carrier levels for efficient energy conversion.

Purpose of the Study:

• To investigate the impact of interfacial electronic band structure engineering in 2D Bi₂Te₃/Si heterostructures.
• To enhance the thermoelectric properties of 2D Bi₂Te₃ by optimizing charge carrier concentration through substrate modification.

Main Methods:

• Fabrication of 2D Bi₂Te₃/Si heterostructures using varying silicon substrates with different work functions.
• Characterization of interfacial electronic band structure and measurement of thermoelectric properties, including electrical conductivity and Seebeck coefficient.

Main Results:

• Decreasing the work function of the Si substrate from 4.6 to 4.06 eV led to simultaneous increases in charge carrier concentration and electron effective mass.
• Electrical conductivity of 2D Bi₂Te₃ on n⁺⁺-Si reached 1250 S·cm^-1, a 90% improvement over the SiO₂/Si counterpart, with a Seebeck coefficient of -103 μV·K^-1.
• The 2D Bi₂Te₃/n⁺⁺-Si heterostructure achieved a power factor of 13.4 μW·cm^-1·K^-2, demonstrating state-of-the-art performance.

Conclusions:

• Interfacial engineering in 2D Bi₂Te₃/Si heterostructures provides an effective strategy for optimizing thermoelectric properties.
• Tuning the substrate's work function is a facile method to enhance charge carrier concentration and improve the overall thermoelectric performance of 2D materials.