Promoting Anderson Localization for Low-Frequency Phonons in SiGe Alloyed Nanowires with Long-Range Correlated...

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Phonon Anderson localization is key for thermal management and energy harvesting.
• Rayleigh scattering governs phonon transport in materials with point disorder.
• Controlling phonon transport in low-dimensional systems is challenging.

Purpose of the Study:

• To investigate design principles for achieving low-frequency phonon Anderson localization.
• To explore the impact of Ge spatial distribution in SiGe nanowires on phonon transport.
• To reduce thermal conductivity in nanostructures.

Main Methods:

• Nonequilibrium Green's function (NEGF) method.
• Simulations of phonon transport in SiGe nanowires with varying Ge spatial correlations.
• Analysis of phonon transmission, localization frequencies, and thermal conductivity.

Main Results:

• Long-range Ge correlations significantly suppress low-frequency phonon transmission (< 2 THz).
• Phonon Anderson localization achieved down to 0.6 THz, stronger than in random systems.
• Thermal conductivity reduced by up to 60% due to suppressed phonon transport.
• Transition from ballistic to diffusive phonon transport observed with spatial correlations.

Conclusions:

• Spatial correlations in Ge distribution are crucial for inducing low-frequency phonon Anderson localization.
• This approach offers a pathway to engineer thermal properties of nanostructures.
• Findings provide insights into heat transfer mechanisms in disordered low-dimensional systems.