Modelling of silicon nanocrystal solids

The physicochemical properties of a spherical semiconductor nanocrystal, intermediate between the molecule and the solid depend on its size. Stacked or dispersed, these nanocrystals are building blocks of new functional materials with tunable properties, particularly appealing for optoelectronics. This thesis takes part in the development of these new materials. It mainly presents a methodology for the simulation of electronic transport in nanocrystal solids within the weak electronic coupling regime. It is applied to a material made of silicon nanocrystals embedded in silicon oxide and considered for photovoltaïc applications. The displacement kinetics of charge carriers is related to the tunneling transfer rate (hopping) between nanocrystals. These rates are calculated within the framework of Marcus theory and take into account the electron-phonon interactions, the effect of the bias field and the electron-electron interactions at short and long range. The calculation of electronic states (electrons and holes) in k.p theory associated with the use of Bardeen's formula provides, compared to previous works, results (mobility or current) in absolute terms. The mobility thus computed is far lower than the results of the literature and encourage to consider other materials. Furthermore, the device simulations show the significant impact of the electrodes on the current-voltage characteristics. Also, a new accelerated kinetic Monte-Carlo algorithm has been adapted in order to reproduce the disorder inherent in the manufacturing process while maintaining a reasonable simulation time. Thus the impact of the size disorder is poor at room temperature while the percolation paths shunt the contribution of other conduction paths. Characterization results compared to simulations tend to show that these paths concentrate carriers and exhibit Coulomb blockade phenomenon. Finally, the absorption cross section is calculated theoretically to obtain the generation rate under illumination. It is similar to the bulk silicon one. And a method employing a Kelvin probe microscope is described to characterize the carrier lifetime, namely the recombination rate. The results thus obtained are consistent with other experimental technics.

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Source https://theses.hal.science/tel-00753248
Author Lepage, Hadrien
Maintainer CCSD
Last Updated May 9, 2026, 16:36 (UTC)
Created May 9, 2026, 16:36 (UTC)
Identifier NNT: 2012ISAL0096
Language fr
Rights https://about.hal.science/hal-authorisation-v1/
contributor Institut des Nanotechnologies de Lyon (INL) ; École Centrale de Lyon (ECL) ; Université de Lyon-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL) ; Université de Lyon-École Supérieure de Chimie Physique Électronique de Lyon (CPE)-Institut National des Sciences Appliquées de Lyon (INSA Lyon) ; Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)
creator Lepage, Hadrien
date 2012-10-22T00:00:00
harvest_object_id 48817ad5-288a-40b2-b36d-380571bf67b2
harvest_source_id 3374d638-d20b-4672-ba96-a23232d55657
harvest_source_title test moissonnage SELUNE
metadata_modified 2026-03-31T00:00:00
set_spec type:THESE