SO phonons in spherical nanostructured quantum dots

A theoretical model for a nanostructured spherical Quantum Dot (QD) is considered, where to a core sphere of semiconductor “1” it is added a concentric spherical layer of semiconductor “2”, while this structure is assumed as imbedded in an infinite medium made of semiconductor “1”. Using a long-wave continuum approach, the so-called dielectric continuum approach, we study the surface optical (SO) phonons associated with the two spherical interfaces of the nanostructure. The possible SO phonon frequencies are analyzed as a function of both the sizes of the structure and the angular momentum quantum number l = 1, 2, …. We also calculate the electric potential provided by the SO phonons and derive an analytical expression for the electron–phonon interaction Hamiltonian. Different possible cases for semiconductors “1” and “2” are discussed, comparisons with previously published works on similar subjects are done and the experimental techniques allowing the possible determination of this kind of phonons are invoked. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)