Interface optical phonon modes and frohlich electron-phonon interaction Hamiltonian in a multi-shell spherical nanoheterosystem

Under dielectric continuum approximation, interface optical (IO) phonon modes and the Frohlich electron-IO phonon interaction Hamiltonian in a multi-shell spherical nanoheterosystem were derived and studied. Numerical calculations on three-layer and four-layer CdS/HgS spherical nanoheterosystems have been performed. Results reveal that there are four IO phonon modes for the three-layer system and six IO phonon modes for the four-layer system. On each interface, there are two IO phonon modes, the frequency of one is between omega(TO,CdS) and omega(LO,CdS), and that of the other is between omega(TO,HS) and omega(LO,HgS). With the increasing of quantum number l, the frequency of each IO mode approaches one of the two frequency values of the single CdS/HgS heterostructure, and the potential for each IO mode is more and more localized at a certain interface, furthermore, the coupling between the electron-IO phonons becomes weaker.