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Sihem Jaziri: Optoelectronic response and excitonic properties of Monolayer MoS2

posted 27 Jul 2015, 00:22 by info admin
1 Laboratoire de Physique de la Matière Condensée, Faculté des Sciences de Tunis, Université Tunis El Manar
2 Laboratoire de Physique des Matériaux, Structures et Propriétés , Faculté des Sciences de Bizerte, Université de Carthage
3 Universitié Joseph Fourier, Grenoble

In the recent years, layered two-dimensional materials have received a lot of interest because of their potential applications in the next generation low-cost solar cells [1] and as possible candidate for replace traditional semiconductors in the next generation of nanoelectronic device[2].The current semiconductor technology requires new materials with definite advantages over traditional silicon, and even grapheme [2]. Transition Metal Dichalcogenides (TMDs) build a new class of layered 2D materials, Molybdenum disulfide (MoS2) is a widely known TMD with strong molecular intralayer bonds, and Van Der Waals interaction enables stacking of the layers. It shows a crossover from indirect- to direct-gap semiconductors depending on the thickness of the material [3,4]. Bulk MoS2 is an indirect bandgap semiconductor with negligible photoluminescence. When the MoS2 crystal is thinned to monolayer, however, a strong photoluminescence emerges, indicating a direct bandgap transition. The 2D character of monolayer TMDs suggests a strong enhancement of the Coulomb interaction. The resulting formation of bound electron-hole pairs, or excitons, can dominate the optical and charge-transport properties. The purpose of this work is to present a detailed characterization of the electronic band structure and optical properties of MoS2 as function of layers number, via first-principles calculations (in the frame work of Density Functional Theory (DFT) based on Linearized Augmented Plane Wave (LAPW) as implemented in WIEN2k code). The 2D excitonic states can be explained by the dielectric screening effect of the Coulomb potential.

[1] K.L. Chopra, P.D. Paulson, V. Dutta, Progr. Photovoltaics: Res. Appl. 12 (2004) 69–92.
[2] E. Scalise, M. Houssa, G. Pourtois , V.V. Afanas0ev ,A. Stesmans, Physica E .56 (2014) 416–421
[3] A. Splendiani , L.Sun et al, Nano Lett 10, (2010), 1271-1275.
[4] Rudren Ganatra and Qing Zhang, ACS NANO.8, (2014) 4074-4099.

I received my received the title of “Docteur d’Etat” in 1996.I am Professor since 2003. I am Member representative of Tunisia of NanoAfNet. I am member of UIPAP networking group of women in Physics and Team Leader of Tunisian Group. I was Vice President of University of Carthage (2008-2011). I am at the head of the group of nanostructures at Laboratoire de Physique de la Matière Condensée. I has been or is being involved in a number of EU and national projects. I co-chaired several National and International Conferences and Symposia. My main research interests are in nanoscience and nanotechnologies. I have been particularly active in the theory of fundamental properties of low-dimensional structures, and in the simulation of advanced nanodevices. In these fields, I have published over 70 papers in refereed international journals, and have participated on international workshops and conferences. I have investigated electronic of few-particle states (excitons and electrons, electron-phonon: polarons states) in quantum dots. A novel research branch connected to the implementation of electronic devices is devoted to exploit the properties of (semi)magnetic nanostructures with spin states. Other work has addressed quantum optic through organic-inorganic heterostructures and hybrid microcavities. More specifically, a novel research branch connected to the implementation of electronic devices is devoted to investigate and exploit the properties of Graphene.

Publications in Graphene
1 A. Daboussi, L. Mandhour, J. N. Fuchs, and S. Jaziri, Tunable zero-energy transmission resonances in shifted graphene bilayer, Phys. Rev. B 89, 085426 (2014).
2 A. Mhamdi, E Ben Salem and S. Jaziri Electronic reflection for a Single-layer Graphene Quantum Well » Solid State Communications Volumes 175–176, 106-113, (2013).