One-dimensional quantum confinement effect modulated thermoelectric properties in InAs nanowires

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Semiconductor nanowires offer unique electronic properties due to quantum confinement.
• Thermoelectric materials can convert heat energy into electrical energy, crucial for waste heat recovery.
• Controlling thermoelectric properties at the nanoscale is key for efficient energy harvesting devices.

Purpose of the Study:

• To investigate the electrical conductance and thermopower of individual indium arsenide (InAs) nanowires.
• To demonstrate gate modulation of thermoelectric properties in InAs nanowires.
• To explore the role of one-dimensional (1D) subband formation in nanostructured thermoelectrics.

Main Methods:

• Synthesis of InAs nanowires using chemical vapor deposition (CVD).
• Electrical conductance and thermopower measurements on individual nanowires.
• Gate voltage modulation of electron chemical potential over a temperature range of 40-300 K.

Main Results:

• Achieved gate modulation of thermopower in ~20 nm diameter InAs nanowires.
• Observed oscillations in thermopower and power factor linked to stepwise conductance increases at low temperatures (<100 K).
• Correlated these oscillations with the formation of quasi-one-dimensional (1D) subbands via gate voltage tuning.

Conclusions:

• Experimentally confirmed the modulation of semiconductor nanowire thermoelectric properties through 1D subband formation in the diffusive transport regime.
• Highlighted energy level broadening due to scattering as a limiting factor for enhanced thermoelectric performance.
• Paved the way for improved nanostructured thermoelectric devices through controlled subband engineering.