Δημοσιεύσεις

Project Acronym: AMONADE
Title: Atomistic MOdelling of NAnostructures and extended DEfects
Affiliation: aristotle university of thessaloniki
Pi: Joseph Kioseoglou
Research Field: physics

Impact of Screw and Edge Dislocations on the Thermal Conductivity of Individual Nanowires and Bulk GaN: a Molecular Dynamics study
by Termentzidis, Konstantinos, Isaiev, Mykola, Salnikova, Anastasiia, Belabbas, Imad, Lacroix, David and Kioseoglou, Joseph
Abstract:
We report on thermal transport properties of wurtzite GaN in the presence of dislocations, by using molecular dynamics simulations. A variety of isolated dislocations in a nanowire configuration are analyzed and found to reduce considerably 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-1 variation in combination with an exponent factor which depends on the material's nature, the type and the structural characteristics of the dislocation's core. Furthermore, the impact of the dislocations density on the thermal conductivity of bulk GaN is examined. The variation and the absolute values of the total thermal conductivity as a function of the dislocation density is 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 in increasing the density of dislocations and it is more pronounced for the systems with edge dislocations. Beside the fundamental insights of the presented results, these could be used also for the identification of the type of dislocations with a simple measurement of the thermal conductivity evolution with the temperature as each type of dislocation has different signature or one could extract the density of dislocations, with a simple measurement of the thermal anisotropy.
Reference:
Impact of Screw and Edge Dislocations on the Thermal Conductivity of Individual Nanowires and Bulk GaN: a Molecular Dynamics study (Termentzidis, Konstantinos, Isaiev, Mykola, Salnikova, Anastasiia, Belabbas, Imad, Lacroix, David and Kioseoglou, Joseph), In Phys. Chem. Chem. Phys., The Royal Society of Chemistry, 2018.
Bibtex Entry:
@article{C7CP07821H,
 author = {Termentzidis, Konstantinos and Isaiev, Mykola and Salnikova, Anastasiia and Belabbas, Imad and Lacroix, David and Kioseoglou, Joseph},
 title = {Impact of Screw and Edge Dislocations on the Thermal Conductivity of Individual Nanowires and Bulk GaN: a Molecular Dynamics study},
 journal = {Phys. Chem. Chem. Phys.},
 year = {2018},
 bibyear = {2018},
 pages = {-},
 publisher = {The Royal Society of Chemistry},
 doi = {10.1039/C7CP07821H},
 url = {http://dx.doi.org/10.1039/C7CP07821H},
 abstract = {We report on thermal transport properties of wurtzite GaN in the presence of dislocations{,} by using molecular dynamics simulations. A variety of isolated dislocations in a nanowire configuration are analyzed and found to reduce considerably 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-1 variation in combination with an exponent factor which depends on the material{'}s nature{,} the type and the structural characteristics of the dislocation{'}s core. Furthermore{,} the impact of the dislocations density on the thermal conductivity of bulk GaN is examined. The variation and the absolute values of the total thermal conductivity as a function of the dislocation density is 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 in increasing the density of dislocations and it is more pronounced for the systems with edge dislocations. Beside the fundamental insights of the presented results{,} these could be used also for the identification of the type of dislocations with a simple measurement of the thermal conductivity evolution with the temperature as each type of dislocation has different signature or one could extract the density of dislocations{,} with a simple measurement of the thermal anisotropy.},
}