Influence of the internal heterostructure on nonlinear absorption spectra for intersubband transitions in spherical quantum dot-quantum well nanoparticles

In this paper, we present the results of our investigation of the electronic spectra and optical properties of one-electron spherical quantum dot-quantum well (QDQW) structure. The investigated QDQW system consists of a CdSe core surrounded by a ZnS shell and a CdSe shell and capped by material of a very high electron potential barrier compared to CdSe, i.e. CdSe/ZnS/CdSe structure. Eigenenergies and corresponding wave functions were calculated by the effective mass approximation. We focused on the one-electron ground state (1s) and the first three excited states. For the allowed transitions, we have calculated the linear and third-order nonlinear intersubband optical absorption coefficients for various structures, i.e. different CdSe core radii, ZnS shell (barrier) widths and CdSe shell widths. A change in the core and shells dimensions induces a change in the electron wave function, followed by a significant change in the energy of state. As a result, the optical properties of this system are strongly dependent on the QDQW structure.