Hybridization of Electron and Hole States in Semiconductor Quantum-Dot Molecules

A novel quantum-dot (QD)-molecule system was demonstrated in which the dot were tunnel coupled through connected quantum wires (QWR). The more efficient tunnel coupling in this integrated QD-QWR system allowed hybridization of electron and hole states, yielding direct-real-space excitionic molecules. The QWR connecting the QDs is found to provide efficient tunnel coupling of the electrons and holes confined in the QD through a 'wavefunction focusing' effect taking place in the 1D QWR. An increase in the coupling between the two QDs results in the energy levels shift from the zero-coupling values and the states approaching hybridization into bonding and antibonding-like wavefunctions. The coupled dots in the model have identical geometry due to the absence of reflection symmetry about the x-y plane, which yields a slightly higher effective potential at the lower dot.