Intrinsic localized modes and their interaction with the plasmon electric field in one-dimensional zinc-blende lattice

In this paper we study the behavior of a diatomic nonlinear one-dimensional lattice which represents the 〈1 1 1〉 direction of a zinc-blende three-dimensional crystal. In these nonlinear lattices are present intrinsic localized modes due to the anharmonicity. These modes lie in the vibrational gap between acoustic and optical linear spectrum. Considering a highly doped GaN semiconductor we examine the coexistence of the localized modes with the electronic plasma oscillations. We derive an expression for the plasmon electric field, we study the dynamics of the anharmonic lattice in presence of this electric field and we calculate the dielectric function of the coupled system. The zeroes of the dielectric function give the frequencies of the coupled modes.