Author(s)

Huanyou Wang^1*, Yaqi Chen¹, Yalan Li^1,2, Xiangyan He¹

¹Department of Physics and Electronic Information Engineering, Xiangnan University, Chenzhou, China.
²College of Physical Science and Technology, Huazhong Normal University, Wuhan, China.

The density functional perturbation theory (DFPT) is employed to study the structure, optical phonon modes and dielectric properties for wurtzite GaN and AlN under hydrostatic pressure. In order to calculate accurately the Born effective charges and high frequency dielectric tensors, we utilize two sum rules to monitor this calculation. The calculated optical phonon frequencies and longitudinal-transverse splitting show an increasing with pressure, whereas the Born effective charges and high frequency dielectric tensors are found to decrease with pressure. In particular, we analysed the reason for discrepancy between this calculation and previous experimental determination of pressure dependence of the LO-TO splitting in AlN. The different pressure behavior of the structural and lattice-dynamical properties of GaN and AlN is discussed in terms of the strengths of the covalent bonds and crystal anisotropy. Our results regarding dielectric Grüneisen parameter are predictions and may serve as a reference.

GaN AlN, Lattice Dynamics, Dielectric, Pressure

Wang, H. , Chen, Y. , Li, Y. and He, X. (2015) Dependence of the Structure, Optical Phonon Modes and Dielectric Properties on Pressure in Wurtzite GaN and AlN. Advances in Materials Physics and Chemistry, 5, 316-324. doi: 10.4236/ampc.2015.58031.