title: Effect of quantum and dielectric confinement on the exciton-exciton interaction energy in type II core/shell semiconductor nanocrystals.
abstract: We study theoretically two electron-hole pair states (biexcitons) in core/shell hetero-nanocrystals with type II alignment of energy states, which promotes spatial separation of electrons and holes. To describe Coulomb interactions in these structures, we apply first-order perturbation theory, in which we use an explicit form of the Coulomb-coupling operator that takes into account interface-polarization effects. This formalism is used to analyze the exciton-exciton interaction energy as a function of the core and shell sizes and their dielectric properties. Our analysis shows that the combined contributions from quantum and dielectric confinement can result in strong exciton-exciton repulsion with giant interaction energies on the order of 100 meV. Potential applications of strongly interacting biexciton states include such areas as lasing, nonlinear optics, and quantum information.
authors.affiliation: Center for Nonlinear Studies (CNLS), Theoretical Division, and Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA. apiryat@lanl.gov
authors.forename: Andrei
authors.initials: A
authors.lastname: Piryatinski
authors.forename: Sergei A
authors.initials: SA
authors.lastname: Ivanov
authors.forename: Sergei
authors.initials: S
authors.lastname: Tretiak
authors.forename: Victor I
authors.initials: VI
authors.lastname: Klimov
mesh_terms: D003460:Crystallization; D004560:Electricity; D008962:Models, Theoretical; D049329:Nanostructures; D011789:Quantum Theory