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Etude théorique de nanofils semiconducteurs

Abstract : Recent breakthroughs in the growth of semiconductor nanowires (SNWs) have opened up great opportunities for nanoscale device applications. SNWs remain semiconducting independent of their diameter and orientation, giving the ability to control their properties by doping. Therefore a large number of experimental works have addressed the problem of doping and of its modulation in SNWs. While there is no doubt that p- and n-type SNWs can be produced, the question of how their electrical conductivity depends on the doping level remains largely open. In fact, most of the works showing good transport properties concern SNWs doped with high impurity concentration, near or above the Mott density. In order to investigate the doping efficiency in SNWs, we present calculations of the electronic structure of donor and acceptor impurities in Si nanowires. We show that their ionization energy increases due to the confinement, the quantum confinement at small sizes (diameter < 5 nm) and above all the so-called dielectric confinement which occurs when there is an important dielectric mismatch between the wire and its surrounding. For SNWs embedded in a material with a low dielectric constant, we obtain that the impurities cannot be ionized at room temperature even for diameters up to several tens of nanometers. We explain the origin of this behavior by considering the effect of the impurity potential and of the self-energy of the carrier, and we make predictions for the ionization energy in different configurations. These results allow us to conclude on the necessity to use heavy doping to obtain good electrical properties in SNWs.
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Contributor : Mamadou Diarra <>
Submitted on : Monday, November 16, 2009 - 4:16:17 PM
Last modification on : Tuesday, December 8, 2020 - 3:31:50 AM
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  • HAL Id : tel-00432564, version 1

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Mamadou Diarra. Etude théorique de nanofils semiconducteurs. Physique [physics]. Université des Sciences et Technologie de Lille - Lille I, 2009. Français. ⟨tel-00432564⟩

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