High Thermoelectric Performance in Polycrystalline GeSiSn Ternary Alloy Thin Films

Area of Science:

• Materials Science
• Solid-State Physics
• Nanotechnology

Background:

• Group IV materials are explored for thin-film thermoelectric generators (TEGs) due to their reliability and human-friendliness.
• Micro-energy harvesting demands efficient and stable thermoelectric materials.

Purpose of the Study:

• Investigate the synthesis and thermoelectric properties of Ge-based ternary alloy thin films (GeSiSn).
• Optimize GeSiSn composition for enhanced thermoelectric performance.

Main Methods:

• Solid-phase crystallization of densified amorphous precursors to form polycrystalline GeSiSn layers.
• Controlled doping via solid-phase diffusion of Gallium (Ga) and Phosphorus (P) to tune carrier concentration.
• Characterization of thermal conductivity, carrier mobility, and power factor.

Main Results:

• Achieved high-quality polycrystalline GeSiSn thin films on insulating substrates.
• Reduced thermal conductivity to 3.1 W m⁻¹ K⁻¹ via alloy scattering.
• Optimized GeSiSn composition (x=0.06, y=0.02) yielded peak power factors of 1160 μW m⁻¹ K⁻² (p-type) and 2040 μW m⁻¹ K⁻² (n-type).
• Obtained dimensionless figures of merit of 0.12 (p-type) and 0.20 (n-type).

Conclusions:

• GeSiSn alloys demonstrate superior thermoelectric performance compared to other environmentally friendly thin films.
• These group IV alloys are highly promising for developing high-performance, reliable thin-film thermoelectric generators for micro-energy harvesting.