The effect of atomistic substitution on thermal transport in large phonon bandgap GaN

Abstract

Recently, wide phonon bandgaps have been found to play an essential role in thermal transport in some semiconductors, such as GaN, where there is a sensitive dependence of the thermal conductivity on isotopes and lattice defects. We explore the effect of carbon and indium substitution on thermal transport in bulk and monolayer GaN from a first-principles approach. Our calculations reveal that the low-frequency phonon modes below the phonon bandgap make dominant contributions to thermal transport. Our phonon mode analysis demonstrates that after the atom substitution, the reduced phonon bandgap and localized vibrations expand the phonon scattering space, thus leading to a large suppression of phonon lifetimes, which is the primary reason for the significant reduction in thermal conductivity. Our findings provide insights on an atomistic scale into the physical mechanism of the effects of atom substitution on thermal transport in GaN, and our results may guide to enhanced thermal management.

Significantly suppressed thermal transport by doping In and Al atoms in gallium nitride

“…al. 45,46 Compared with Al-doped GaN, the In atom induced modification of the phonon dispersion of GaN occurs in the range of 2–7 THz, which has little effect on phonon bandgap, leading to the equal bandgap value with GaN. We consider that the independent phonon branch contributed by the Al atom is related to the smaller atomic mass of Al.…”

Different Effects of Mg and Si Doping on the Thermal Transport of Gallium Nitride

“…The thermal conductivities of InGaN and AlGaN alloys were studied using the virtual crystal model, while the specific doping structures are ignored (Ma et al, 2016). Only the thermal transport properties of GaN doped with In and C have been studied based on the first-principles calculation with doping structures (Li and Wang, 2021). In fact, substitutional dopants introduce mass perturbations and extended bond perturbations (Fava et al, 2021), due to the difference in atomic masses of host and substituting atoms and the distortion produced by the dopant.…”

Effect of atomic substitution and structure on thermal conductivity in monolayers H-MN and T-MN (M = B, Al, Ga)

“…Factors influencing k and methods of control have long been a focus of research. For example, the reflection symmetry in graphene can reduce phonon scattering, 25 thereby enhancing its k. On the other hand, the presence of lone pair electrons can increase phonon anharmonicity, leading to a decrease in the material's k. [26][27][28][29] In materials like BAs, four-phonon scattering has also been found to have a significant impact on k. [30][31][32][33] Furthermore, there are several methods available to control the k of materials, such as atomic substitution, [34][35][36] doping, [37][38][39][40] applying strain, [41][42][43][44] and using electric fields, 45,46 among others. These studies provide essential theoretical foundations and practical methods for our understanding and control of a material's k.…”

“…26–29 In materials like BAs, four-phonon scattering has also been found to have a significant impact on κ . 30–33 Furthermore, there are several methods available to control the κ of materials, such as atomic substitution, 34–36 doping, 37–40 applying strain, 41–44 and using electric fields, 45,46 among others. These studies provide essential theoretical foundations and practical methods for our understanding and control of a material's κ .…”