Phonon Interference Effects in GaAs-GaP Superlattice Nanowires.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Nanomaterials' functional properties are key for technological advancements.
• Superlattices, with periodic material repetitions, offer tunable properties.
• Understanding thermal transport in nanostructures is vital for device applications.

Purpose of the Study:

• To investigate the phonon interference effect on thermal transport in GaAs-GaP superlattice nanowires.
• To analyze how superlattice period influences thermal conductivity.
• To explore the transition from coherent to incoherent phonon transport.

Main Methods:

• Fabrication and characterization of GaAs-GaP superlattice nanowires using high-resolution transmission electron microscopy.
• Thermal conductivity measurements using the thermal bridge method across varying superlattice periods (4.8–23.3 nm).
• Computational analysis using *ab initio* lattice dynamics and nonequilibrium molecular dynamics simulations.

Main Results:

• Observed a minimum in thermal conductivity as a function of superlattice period, indicating a crossover in phonon transport.
• This crossover effect persists up to room temperature, unaffected by surface boundaries or phonon-phonon scattering.
• Experimental findings were validated by theoretical calculations.

Conclusions:

• Demonstrated the crossover from coherent to incoherent phonon transport in GaAs-GaP superlattice nanowires.
• Highlighted the wave-like and particle-like behavior of phonons in these nanostructures.
• Showcased the potential for engineering thermal properties via precise control of superlattice structures.