Confinement-induced valence-band mixing in CdS quantum dots observed by two-photon spectroscopy

Kang, K. I.; McGinnis, B. P.; Sandalphon,; Hu, Yuan; Koch, S. W.; Peyghambarian, N.; Mysyrowicz, A.; Liu, L. C.; Risbud, S. H.

doi:10.1103/physrevb.45.3465

Cited by 74 publications

(44 citation statements)

References 17 publications

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“…The above described model has been modified and extended by other authors concerning the existence of a bound state of two electron-hole pairs within a single dot (biexciton) (Hu et al, 1990), and confinement-induced band mixing (Kang et al, 1992).…”

Section: Theorymentioning

confidence: 99%

Quantum dot containing nanocomposite thin films for photoluminescent solar concentrators

et al. 2007

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Silicon oxide films containing CdS quantum dots have been deposited on glass substrates by a sol-gel dip-coating process. Hereby the CdS nanocrystals are grown during the thermal annealing step following the dip-coating procedure. Total hemispherical transmittance and reflectance measurements were carried out by means of a spectrophotometer coupled to an integrating sphere. For CdS-rich films, an absorption edge at photon energies in the vicinity of the band gap value of bulk CdS is observed. For lower CdS concentrations, the absorption edge shifts to higher photon energies, as expected for increasing quantum confinement. The samples show visible photoluminescence which is concentrated by total internal reflection and emitted at the edges of the substrate. The edge emission has been characterized by angle-dependent photoluminescent (PL) spectroscopy. Information on the lateral energy transport within the sample can be extracted from spectra obtained under spatial variation of the spot of excitation. The color of the photoluminescence can be tuned by varying the annealing temperature which governs crystal growth and thus the cluster size distribution. The characteristic features observed in the PL spectra clearly exhibit a blueshift for lower annealing temperatures, confirming the presence of quantum size effects.Advantages of the proposed concept of quantum dot containing coatings on glass panes for photoluminescent solar concentrators are the high potential for low-cost fabrication on the large scale and the suitability for architectural integration.

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Section: Theorymentioning

confidence: 99%

Quantum dot containing nanocomposite thin films for photoluminescent solar concentrators

et al. 2007

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“…En régime non résonant, c'est cette en négligeant la recombinaison des porteurs à l'échelle de la picoseconde, a est la section efficace d'absorption des porteurs libres. Les règles de sélection sont différentes pour l'absorption à deux photons et pour l'absorption linéaire [26]. Les valeurs des paramètres ß et a ont été déduites de mesures de la transmission en fonction de l'intensité incidente.…”

Section: Le Régime Non Résonantunclassified

Les nanocristaux semi-conducteurs ou boîtes quantiques

Ricard

1998

l'Optique Non Linéaire Et Ses Matériaux

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Résumé : Nous discutons ici des propriétés optiques linéaires et non linéaires de colloïdes ou de verres contenant des nanocristaux semi-conducteurs, l'exemple choisi étant CdSe. Le confinement des porteurs conduit à un spectre de raies élargies surtout par la grande dispersion de taille des nanocristaux. La non-linéarité qui intéresse les applications est l'effet Kerr statique ou optique. Dans ce dernier cas, il faut distinguer le régime résonant où l'effet dominant est un effet de population et le ré-gime non résonant où le déplacement radiatif est à l'origine de l'indice non linéaire. L'absorption à deux photons est également considérée.

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“…The fit gives d= 2.06 ± 0.13, and hence the expected quadratic behaviour. It was previously found for quantum wells and quantum wires that the PL followed a quadratic dependence on the excitation power under NE [63,64] suggesting a two-photon absorption process. These findings indicate that higher order processes are involved in the NE in these dots.…”

Section: Nonlinear Excitation Of Single Ingan/gan Qdsmentioning

confidence: 99%

“…For example, two-photon absorption (TPA) has been investigated in QWs [62], quantum wires [63] and ensembles of semiconductor nanocrystals in a glass matrix [64]. In fact, this technique provides the possibility of exciting transitions that are forbidden for one-photon excitation (OPE).…”

Section: Nonlinear Excitation Of Single Ingan/gan Qdsmentioning

confidence: 99%