Phonon properties and thermal conductivity of GaN nanofilm under prestress and surface/interface stress

This work investigates the effects of surface/interface stress and prestress fields on phonon thermal conductivity of wurtzite-GaN nanofilms theoretically. The elasticity model is applied to describe the phonon dispersion relations of spatially confined GaN nanofilms. The acoustoelastic effects and surface/interface stress effects are accounted for in calculating the phonon properties and thermal conductivity. Theoretical results show that the prestress and surface/interface stress can alter significantly the phonon properties such as the phonon dispersion relations, resulting in modification of thermal conductivity in GaN nanofilms. In addition, the prestress and surface/interface stress can change the dependence of thermal conductivity on the geometrical size and temperature. These results can be useful in controlling the thermal conductivity based on the strain/stress engineering in GaN nanostructures-based electronic devices.