Surface and interface phonon-polaritons in freestanding quantum well wire systems of polar ternary mixed crystals

•We study surface and interface phonon-polaritons in freestanding QWW systems.•Polariton modes located in the three forbidden bands of bulk phonon-polaritons.•Polariton properties depend on the geometric structure and composition of the TMC.•One or two mode behaviors of surface and interface phonon-polaritons are seen.

The surface and interface phonon-polaritons in freestanding rectangular quantum well wire systems consisting of polar ternary mixed crystals are investigated in the modified random-element-isodisplacement model and the Born–Huang approximation, based on the Maxwell's equations with the boundary conditions. The numerical results of the surface and interface phonon-polariton frequencies as functions of the wave-vector, geometric structure, and the composition of the ternary mixed crystals in GaAs/AlxGa1−xAs and ZnxCd1−xSe/ZnSe quantum well wire systems are obtained and discussed. It is shown that there are 10 and 8 branches of surface and interface phonon-polaritons in the two quantum well wire systems respectively. The effects of the “two-mode” and “one-mode” behaviors of the ternary mixed crystals on the surface and interface phonon-polariton modes are shown in the dispersion curves.