Interface phonons in cylindrical quantum dot heterostructure

The top interface optical (TIO) and side interface optical (SIO) phonon modes of a cylindrical GaAs/ AlxGa1−xAs quantum dot are derived within the framework of dielectric continuum approximation. Results reveal that, in the case of taking the “two-mode” behavior of the AlxGa1−xAs material into account, there exist eight branches of TIO phonon modes and four branches of SIO phonon modes. The dispersion frequencies of TIO or SIO phonon modes sensitively depend on the Al mole fraction x in the AlxGa1−xAs material. With increasing wavevector q (κ), the frequency of each TIO (SIO) mode approaches one of the two frequency values of the single AlxGa1−xAs heterostructure.