Nanostructured bulk Si for thermoelectrics synthesized by surface diffusion/sintering doping

Area of Science:

• Materials Science
• Nanotechnology
• Thermoelectric Energy Conversion

Background:

• Nanostructured bulk silicon (bulk nano-Si) is a promising thermoelectric material due to its abundance and low toxicity.
• Conventional synthesis methods for bulk nano-Si often lead to undesirable oxidation, degrading thermoelectric performance and requiring expensive preventative techniques.

Purpose of the Study:

• To develop a simple, cost-effective, and scalable method for synthesizing high-performance bulk nano-Si for thermoelectric applications.
• To address the challenge of oxidation during bulk nano-Si synthesis.

Main Methods:

• A novel Surface Diffusion/Sintering Doping (SDSD) method was employed, utilizing Si nanoparticles with native oxide layers.
• The SDSD process involves two steps: applying a molecular precursor containing a doping element to the oxide layer and subsequent sintering.
• During sintering, the doping element diffuses through the oxide layer, forming conductive paths and enhancing carrier concentration and mobility.

Main Results:

• The SDSD method successfully synthesized P-doped bulk nano-Si with high carrier concentration and high carrier mobility.
• The nanostructured nature of the synthesized material resulted in low lattice thermal conductivity (κlat).
• The synthesized P-doped bulk nano-Si exhibited good overall thermoelectric performance.

Conclusions:

• The SDSD method provides a cost-effective and scalable approach for producing advanced bulk nano-Si thermoelectric materials.
• The technique effectively utilizes the native oxide layer of Si nanoparticles to achieve desired doping levels and nanostructures.
• SDSD is suitable for mass production, paving the way for wider application of silicon-based thermoelectrics.