GaAs/GaP Superlattice Nanowires for Tailoring Phononic Properties at the Nanoscale: Implications for Thermal Engineering

TL;DR

This study demonstrates how GaAs/GaP superlattice nanowires can be engineered to control phononic and electronic properties, providing new avenues for thermal management at the nanoscale through experimental and theoretical analysis.

Contribution

It introduces a method to tune phonon and electronic properties of nanowires using superlattice periodicity, supported by experimental Raman spectroscopy and ab initio calculations.

Findings

Phonon dispersion relations are modified in superlattice nanowires.

Phonon frequencies can be tuned by adjusting superlattice periodicity.

The electronic bandgap is reduced in superlattice nanowires compared to bulk materials.

Abstract

The possibility to tune the functional properties of nanomaterials is key to their technological applications. Superlattices, i.e., periodic repetitions of two or more materials in different dimensions are being explored for their potential as materials with tailor-made properties. Meanwhile, nanowires offer a myriad of possibilities to engineer systems at the nanoscale, as well as to combine materials which cannot be put together in conventional heterostructures due to the lattice mismatch. In this work, we investigate GaAs/GaP superlattices embedded in GaP nanowires and demonstrate the tunability of their phononic and optoelectronic properties by inelastic light scattering experiments corroborated by ab initio calculations. We observe clear modifications in the dispersion relation for both acoustic and optical phonons in the superlattices nanowires. We find that by controlling the superlattice periodicity we can achieve tunability of the phonon frequencies. We also performed wavelength-dependent Raman microscopy on GaAs/GaP superlattice nanowires and our results indicate a reduction in the electronic bandgap in the superlattice compared to the bulk counterpart. All our experimental results are rationalized with the help of ab initio density functional perturbation theory (DFPT) calculations. This work sheds fresh insights into how material engineering at the nanoscale can tailor phonon dispersion and open pathways for thermal engineering.