[Invited] Quantum and dielectric confinement effects on the absorption strength in semiconductors

Delerue, Christophe; Vanmaekelbergh, Daniel; Prins, P. Tim; Alimoradi Jazi, M.; Houtepen, Arjan J.; Evers, Wiel H.

Type de document :

Autre communication scientifique (congrès sans actes - poster - séminaire...): Communication dans un congrès avec actes: Conférence invitée

Titre :

[Invited] Quantum and dielectric confinement effects on the absorption strength in semiconductors

Auteur(s) :

Delerue, Christophe [Auteur]

Physique - IEMN [PHYSIQUE - IEMN]
Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 [IEMN]
Vanmaekelbergh, Daniel [Auteur]
Debye Institute for Nanomaterials Science
Prins, P. Tim [Auteur]
Universiteit Utrecht / Utrecht University [Utrecht]
Alimoradi Jazi, M. [Auteur]
Universiteit Utrecht / Utrecht University [Utrecht]
Houtepen, Arjan J. [Auteur]
Delft University of Technology [TU Delft]
Evers, Wiel H. [Auteur]
Delft University of Technology [TU Delft]

Titre de la manifestation scientifique :

nanoGe Fall Meeting, NGFM19, Symposium #Sol2D19 - Two Dimensional Layered Semiconductors

Ville :

Berlin

Pays :

Allemagne

Date de début de la manifestation scientifique :

2019-11-04

Discipline(s) HAL :

Physique [physics]/Matière Condensée [cond-mat]

Résumé en anglais : [en]

Recent advances in colloidal synthesis and assembly1-3 allows a comparison of the strength of light absorption of semiconductor nanocrystals in three distinct electronic phases: (i) as non-interacting individual nanocrystals ...
Lire la suite >Recent advances in colloidal synthesis and assembly1-3 allows a comparison of the strength of light absorption of semiconductor nanocrystals in three distinct electronic phases: (i) as non-interacting individual nanocrystals with strong three-dimensional quantum confinement dispersed in solution, (ii) as ligand-separated nanocrystals present in an ordered monolayer, and (iii) as nanocrystals epitaxially connected in a monolayer superlattice. We performed quantitative absorptance measurements on these three different samples, for the case of PbSe (band gap in the IR) and CdSe (band gap in the visible). The light absorption cross section of PbSe nanocrystals in a hexagonal monolayer is 5-10 fold increased versus nanocrystals in solution; this is due to far-field polar coupling, which reduces the dielectric screening of the electric field in a NC monolayer. The absorption cross section is further enhanced in superlattices as the epitaxial connection results in a two-dimensional electronic system, and thus complete quenching of dielectric screening. Nanocrystal monolayer superlattices of PbSe and CdSe on quartz show 1.6 % absorptance, a value directly related to the fine structure constant. This “quantum of light absorption” has been reported for several other two-dimensional systems, from graphene4 to III-V semiconductor quantum wells5, and explained with Fermi’s golden rule and the effective mass approximation5. We calculated the absorptance of two-dimensional II-VI and IV-VI semiconductors and superlattices with atomistic tight-binding theory, resulting in values close to the absorptance quantum.Lire moins >

Langue :

Anglais

Comité de lecture :

Oui

Audience :

Internationale

Vulgarisation :

Non

Collections :

Institut d'Électronique, de Microélectronique et de Nanotechnologie (IEMN) - UMR 8520

Source :

Harvested from HAL

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