Full text loading...
(a) Schematic drawing of the formation of bonding and antibonding states in coupled QDs. (b) Excitation level diagram using a quantum mechanically coupled QD system. ∣00⟩, ∣01⟩, ∣10⟩, and ∣11⟩ denote the crystal ground state, the exciton state, the exciton state and the exciton molecule state consisting of and excitons, respectively. indicates the binding energy of the exciton molecule.
(a) One-color PLE spectra of a single pair of coupled QDs with . and indicate bonding and antibonding PL groups, and and denote different peaks in the same PL group, respectively. The inset shows the PL spectrum of coupled QDs under PLE measurement excited at 1.41 eV (absorption band of wetting layer), for which the excitation intensity was set sufficiently low such that multiple excitons could not be excited. (b) PL spectra of coupled QDs excited by one-color and two-color excitation. and indicate the excitation energy of the two laser sources as indicated in (a).
(a) The one-color excitation power dependence of the PL spectra, where the excitation energy and power are 1.41 eV and , respectively. The inset shows integral PL intensity as a function of excitation power, where indicates the exponent to the excitation power. (b) The two-color excitation power dependence of the PL intensity of , where the and axes shows the excitation power at and energies, respectively.
One-color and two-color PLE spectra of the coupled QDs. The bottom and second from the bottom spectra are the one-color PLE spectra of and exciton, respectively. The top and second from the top spectra are the two-color PLE spectra of state (exciton molecule) and exciton, respectively, where the exciton was pumped constantly at the energy by another laser source. The inset is a schematic drawing of the concept of two-color PLE measurement in a coupled QD system.
Article metrics loading...