Partners and International Organizations
(English)
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A, B, BG, CZ, DK, FIN, F, D, GR, H, IRL, I, NL, PL, RO, E, S, CH, GB
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Abstract
(English)
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The application of quantum confined semiconductor nanostructures such as quantum wells (QWs),quantum wires (QWRs) and quantum dots (QDs) in optoelectronic devices requires good understanding of the interaction of the confined charge carriers with optical fields. To this end, we have constructed several types of semicondcutor quantum nanostructures and investigated experimentally their optical emission properties. Strained GaAs/InGaAs V-groove QWRs were incorporated in high-finesse optical micro cavities of different photon dimensionality (photonic wells, wires and dots). The photoluminescence spectra of the QWRs were dramatically modified by the photon confinement, and the recombination lifetime of excitons in the QWRs was found to be shorter in the optical cavity than in 'free space' (Purcell effect). Light emitting diodes and lasers incorporating lattice matched GaAs/AlGaAs and strained InGaAs/AlGaAs V-groove QWRs were also fabricated and studied. Measurements in high magnetic fields showed that light emission in these structures is dominated by excitonic recombination. The luminescence from GaAs/AlGaAs QDs grown in inverted pyramids was studied as well. The photoluminescence spectra of single QDs reveals transitions corresponding to new, charged excitonic complexes that are made stable by the three-dimensional quantum confinement. The spectra of single QDs were found to be extremely sensitive to the impurity environment in the vicinity of the dot. The luminescence spectra of a QD can thus be utilized to obtain information on its solid-state environment. Finally, novel photonic crystal heterostructures based on coupled arrays of vertical cavity surface emitting lasers were fabricated and employed in demonstrating the confinement of photon envelope functions.
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