On the role of piezoelectricity in phonon properties and thermal conductivity of GaN nanofilms

摘要

The effect of piezoelectricity on phonon properties and thermal conductivity of gallium nitride(Ga N)nanofilms is theoretically investigated. The elasticity model is utilized to derive the phonon properties in spatially confined Ga N nanofilms. The piezoelectric constitutive relation in Ga N nanofilms is taken into account in calculating the phonon dispersion relation. The modified phonon group velocity and phonon density of state as well as the phonon thermal conductivity are also obtained due to the contribution of piezoelectricity. Theoretical results show that the piezoelectricity in Ga N nanofilms can change significantly the phonon properties such as the phonon group velocity and density of states,resulting in the variation of the phonon thermal conductivity of Ga N nanofilms remarkably. Moreover,the piezoelectricity of Ga N can modify the dependence of thermal conductivity on the geometrical size and temperature. These results can be useful in modeling the thermal performance in the active region of Ga N-based electronic devices.