High Power Factor in Polycrystalline InGaSb Thin Films via Nanoscale Compositional Fluctuations

Area of Science:

• Materials Science
• Solid State Physics

Background:

• III-V compound semiconductors offer potential for thin-film thermoelectric applications due to their narrow bandgaps.
• Thermoelectric materials convert heat energy into electrical energy and vice versa, crucial for waste heat recovery and solid-state cooling.

Purpose of the Study:

• To investigate the impact of deposition parameters on the thermoelectric properties of polycrystalline Indium Gallium Antimonide (InGaSb) thin films.
• To identify key growth factors controlling phase competition and nanoscale composition for optimizing thermoelectric performance.

Main Methods:

• Systematic investigation of polycrystalline InGaSb thin films deposited on glass substrates.
• Modulation of Indium (In) flux and deposition temperature to control film microstructure and composition.
• Raman spectroscopy analysis to evaluate structural disorder and nanoscale features.

Main Results:

• Deposition temperature and In flux were identified as critical parameters influencing phase competition and nanoscale compositional fluctuations.
• Controlled formation of In-rich precipitates and tuning of matrix composition were achieved by varying In supply.
• Increased structural disorder at higher deposition temperatures (560 °C) correlated with an enhanced Seebeck coefficient.
• A high thermoelectric power factor of 1200 µW m⁻² K⁻² was achieved near room temperature.

Conclusions:

• Growth-parameter-driven control over microstructure and phase is an effective strategy for enhancing thermoelectric performance in multicomponent III-V thin films.
• Optimized InGaSb thin films demonstrate significant potential for efficient thermoelectric energy conversion applications.