Propagating optical phonons and their properties in GaN/AlN quantum wells

Department of Physics, Shaanxi University of Technology, Hanzhong, 723001 Shaanxi, P.R. China

Corresponding author: sxlgwendeng@163.com

Received: 6 September 2010
Accepted: 8 December 2010
Published online: 13 April 2011

Abstract

Within the framework of the dielectric-continuum model, the equations of motion for p-polarization field in wurtzite quantum well are solved for the propagating optical phonon modes. The polarization eigenvector and the dispersion relation are derived by using the determinate method. The dispersion relation and phonon modes properties of the propagating optical phonons are investigated for GaN/AlN single QW. The numerical results show that the propagating phonons have a quantization character by a quantum number n that define its order. The propagating optical phonons are more dispersive for decreasing n, and the bands formed by the dispersion curves are narrower for higher order modes. The wave vector and width of quantum well have more important effect on phonon energy, with the increase of wave vector or width of quantum well, the energy of propagating optical phonon modes decrease in TO domain (between A₁ (TO) and E₁ (TO) frequency of GaN), and increase in LO domain (between GaN A₁ (LO) and E₁ (LO) frequency of GaN). The strain effects of QW structures have clear influence on the dispersion behavior of propagating optical phonons. The frequency of the propagating optical phonon modes is increased due to the strains of the QW structure.