Achieving Extraordinary Power Factors in GeTe Epitaxial Films through Carrier Transport Engineering

Area of Science:

• Materials Science
• Solid State Physics
• Nanotechnology

Background:

• Germanium Telluride (GeTe) based films are crucial for thermoelectric applications.
• Achieving high carrier mobility while reducing hole density in GeTe films is a significant challenge.

Purpose of the Study:

• To fabricate high-crystalline quality GeTe-based films with enhanced electrical properties.
• To overcome the limitations of hole density and carrier mobility in GeTe films for improved thermoelectric performance.

Main Methods:

• Utilized molecular beam epitaxy (MBE) with a Bi2Te3/GeTe double-layer buffer.
• Optimized low substrate temperature (503 K) and Te/GeTe flux ratios (0.25/1).
• Incorporated trace amounts of Antimony Telluride (Sb2Te3) to introduce SbTe substitutional defects.

Main Results:

• Achieved high-crystalline quality GeTe-based films.
• Successfully reduced hole density to 2.57 × 10^20 cm^-3 and increased carrier mobility to 96.53 cm^2 V^-1 s^-1.
• Obtained a peak power factor of 3.36 mW m^-1 K^-2 at room temperature and an average of 4.15 mW m^-1 K^-2 from 300-475 K.

Conclusions:

• The optimized fabrication process, including the buffer layer and controlled incorporation of Sb2Te3, significantly enhances GeTe film properties.
• The achieved electrical properties outperform previous reports, indicating great potential for GeTe-based materials in near-room-temperature thermoelectric applications.