Nanowires with dislocations for ultralow lattice thermal conductivity

Al-Ghalith, Jihong; Ni, Yuxiang; Dumitrică, Traian

doi:10.1039/c6cp00630b

Cited by 19 publications

(21 citation statements)

References 35 publications

(37 reference statements)

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“…In recent years, Dumitricȃ et al investigated the relationship between screw dislocation and the electrical and thermal properties of a series of materials, including ZnO and Si nanowires and nanotubes, SiC, PbSe, and SiGe nanowires [6][7][8][9][10][11]. The observed narrower bandgaps and lower thermal conductivity in nanowires induced by screw dislocations bring new perspectives to the nanoscale design of electronic and thermoelectric materials.…”

Section: Introductionmentioning

confidence: 99%

Screw dislocation induced phonon transport suppression in SiGe superlattices

Zhang

Xiong

et al. 2019

Phys. Rev. B

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Screw dislocations are known to impede the thermal transport of homogeneous nanowires by reducing the phonon relaxation time without affecting the phonon group velocity. By using molecular dynamics simulations in this study, we show that the impact of screw dislocation on the thermal conductivity of the SiGe superlattice nanowires depends on the period length. The analysis of phonon transmission spectra and phonon mean free paths indicate that strong phonon-screw dislocation scatterings occur for phonons in the frequency range of 3-8 THz. The screw dislocations change the phonon scattering mechanisms, which is the main cause of the thermal conductivity reduction. Contrary to the case of homogeneous nanowires, a sizable decrease in the phonon group velocity is found in superlattices with screw dislocations. This phenomenon is attributed to the larger number of Si-Ge bonds in the vicinity of the interface due to the slipping of the atomic planes. In contrast to the decreased thermal conductivity, the phonon propagation in the interface region of the nanowires is enhanced by screw dislocations. Our findings provide critical insights into the understanding of dislocation-heat transfer relationship in materials, especially in heterostructures where interfaces are vital for thermal transport.

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Section: Introductionmentioning

confidence: 99%

Screw dislocation induced phonon transport suppression in SiGe superlattices

Zhang

Xiong

et al. 2019

Phys. Rev. B

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“…The influence of threading dislocations on thermal transport has not been elucidated yet. However, the few existing theoretical studies focus solely on the impact of screw dislocations [11,12,13]. Dislocations and compositional inhomogenities create energy states in the gap as well as band fluctuations.…”

Section: Introductionmentioning

confidence: 99%

Impact of screw and edge dislocations on the thermal conductivity of individual nanowires and bulk GaN: a molecular dynamics study

Termentzidis

Isaiev

Salnikova

et al. 2018

Phys. Chem. Chem. Phys.

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We report the thermal transport properties of wurtzite GaN in the presence of dislocations using molecular dynamics simulations. A variety of isolated dislocations in a nanowire configuration are analyzed and found to considerably reduce the thermal conductivity while impacting its temperature dependence in a different manner. Isolated screw dislocations reduce the thermal conductivity by a factor of two, while the influence of edge dislocations is less pronounced. The relative reduction of thermal conductivity is correlated with the strain energy of each of the five studied types of dislocations and the nature of the bonds around the dislocation core. The temperature dependence of the thermal conductivity follows a physical law described by a T variation in combination with an exponent factor that depends on the material's nature, type and the structural characteristics of the dislocation core. Furthermore, the impact of the dislocation density on the thermal conductivity of bulk GaN is examined. The variation and absolute values of the total thermal conductivity as a function of the dislocation density are similar for defected systems with both screw and edge dislocations. Nevertheless, we reveal that the thermal conductivity tensors along the parallel and perpendicular directions to the dislocation lines are different. The discrepancy of the anisotropy of the thermal conductivity grows with increasing density of dislocations and it is more pronounced for the systems with edge dislocations. Besides the fundamental insights of the presented results, these could also be used for the identification of the type of dislocations when one experimentally obtains the evolution of thermal conductivity with temperature since each type of dislocation has a different signature, or one could extract the density of dislocations with a simple measurement of thermal anisotropy.

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“…Moreover, the axial screw dislocation spirally threads the vdW layers, which can improve the electron conductivity along the cross-plane direction 23 . The presence of the dislocation and the twist also enhance the scattering of phonons, lowering the thermal conductivity 28 . The combination of increasing electron conductivity while decreasing thermal conductivity is attractive for thermoelectrics.…”

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confidence: 99%