Optical Interface Phonon in Graded Quantum Well Structures

The behaviour of optical interface phonon is investigated first for the graded quantum well of Ga_l-xAl_xAs in the dielectric continuum model. It is found that the behaviour of interface phonon modes is quite different from that in square quantum well structure. The dispersions of the interface modes are sensitive to the gradient of the graded quantum well structure, and the symmetry of modes can be changed greatly, which is important for phonon-related phenomena.