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Dependence of the structure, optical phonon modes and dielectric properties on pressure in wurtzite GaN and AlN

H. WANG1,2,* , Y. XIE1, Y. LI1,3, N. ZHANG1

Affiliation

  1. Department of Physics and Electronic Information Engineering, Xiangnan University, Chenzhou 423000, China
  2. School of physics and electronics, Central South University, Changsha 410083, China
  3. College of physical science and technology, Huazhong Normal University, Wuhan 430079, China

Abstract

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..

Keywords

GaN AlN; Lattice dynamics; Dielectric; Pressure.

Submitted at: July 28, 2014
Accepted at: Sept. 9, 2015

Citation

H. WANG, Y. XIE, Y. LI, N. ZHANG, Dependence of the structure, optical phonon modes and dielectric properties on pressure in wurtzite GaN and AlN, Journal of Optoelectronics and Advanced Materials Vol. 17, Iss. 9-10, pp. 1302-1308 (2015)