MULTIBAND THEORY OF QUANTUM-DOT QUANTUM-WELLS - DIM EXCITONS, BRIGHT EXCITONS, AND CHARGE SEPARATION IN HETERONANOSTRUCTURES

Electron, hole, and exciton states of multishell CdS/HgS/CdS quantum-d ot quantum-well nanocrystals are determined by use of a multiband theo ry that includes valence-band mixing, modeled with a six-band Luttinge r-Kohn Hamiltonian, and nonparabolicity of the conduction band. The mu ltiband theory correctly describes the recently observed dim-exciton g round state and the lowest, optically active, bright-exciton states. C harge separation in pair states is identified. Previous single-band th eories could not describe these states or account for charge separatio n. [S0163-1829(98)52108-X].