  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 were analyzed and found to reduce
considerably the thermal conductivity while impacting its temperature
dependence in a different manner. We demonstrate that 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 even the absolute values of the total thermal
conductivity as a function of the dislocation density is similar for both types
of dislocations. The thermal conductivity tensors along the parallel and
perpendicular directions to the dislocation lines are analyzed. 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.
