Thermal Conductivity of GaN Nanowires and Heterostructures
Eastern Illinois University, US
Keywords: nanowires, thermal conductivity, heterostructures, phonon engineering
Abstract:GaN-based nanostructures have important applications in high-power devices. A crucial factor that affects the performance of these devices is self heating. Thermal performance simulations of such devices depend on accurate knowledge of the thermal conductivity, k, of the device material. Guthy et al. recently reported measurements of k of GaN nanowires. The observed k is shown to be lower (by a factor of ~5 in some case) than the theoretical predictions. To explain the observed unusually low k, in this poster, we report the development of a detailed model for the thermal conductivity of GaN nanowires. Compared to previous models, we include the effects of the impurity, the boundary scattering, the modification of the phonon group velocity, and also the following important factors: (i) change in the phonon density-of-states and (ii) change in the non-equilibrium phonon distribution in a nanowire. Comparisons with experimental data are analyzed. Also in this poster, we report our recent work on the thermal conductivity of AlN/GaN/AlN heterostructures. Our results quantitatively show that it is possible to improve heat conduction in semiconductor nanostructures through phonon spectrum engineering, in agreement with other recent studies. The results are important for thermal management of nanoscale devices.