Trani, Fabio
(2005)
Electronic and optical properties of silicon nanocrystals:
a Tight Binding study.
[Tesi di dottorato]
(Inedito)
| Tipologia del documento: |
Tesi di dottorato
|
| Lingua: |
English |
| Titolo: |
Electronic and optical properties of silicon nanocrystals:
a Tight Binding study |
| Autori: |
| Autore | Email |
|---|
| Trani, Fabio | [non definito] |
|
| Data: |
2005 |
| Tipo di data: |
Pubblicazione |
| Numero di pagine: |
120 |
| Istituzione: |
Università degli Studi di Napoli Federico II |
| Dipartimento: |
Scienze fisiche |
| Scuola di dottorato: |
Fisica fondamentale e applicata |
| Dottorato: |
Struttura della materia |
| Ciclo di dottorato: |
17 |
| Coordinatore del Corso di dottorato: |
| nome | email |
|---|
| Tagliacozzo, Arturo | [non definito] |
|
| Tutor: |
| nome | email |
|---|
| Ninno, Domenico | [non definito] |
|
| Data: |
2005 |
| Numero di pagine: |
120 |
| Settori scientifico-disciplinari del MIUR: |
Area 02 - Scienze fisiche > FIS/07 - Fisica applicata (a beni culturali, ambientali, biologia e medicina) |
[error in script]
[error in script]
| Depositato il: |
01 Ago 2008 |
| Ultima modifica: |
30 Apr 2014 19:22 |
| URI: |
http://www.fedoa.unina.it/id/eprint/73 |
| DOI: |
10.6092/UNINA/FEDOA/73 |
Abstract
From the theoretical point of view, the silicon nanocrystal physics still today
is not a completely clear subject. While the quantum confinement effect has
been recognized as the major cause of the photoluminescence, many doubts
remain on the way in which the phenomenon takes place in real nanocrystals.
This thesis is the result of a deep work in the understanding of the optical
properties of silicon nanocrystals. A Tight Binding method has been used for
studing the energy levels and the dielectric properties of spherical and ellipsoidal
silicon nanocrystals. The method is very efficient, allowing the study
of structures with more than 10000 atoms, and being able to reproduce with
a great accuracy the Bulk Silicon dielectric function. The comparison with
the experimental results shows that for Si nanocrystals the method works
well, both for the energy gap and the absorption spectra prediction. The
optical gap, the imaginary part of the dielectric function, the static dielectric
function, and the radiative electron-hole recombination times have been
calculated for a set of silicon spheres, on increasing their size. An interesting
feature is the existence of an energy gap between the energy of the first
transition and the threshold of the absorption cross section. This is an indication
that the electronic features of the bulk silicon are always reflected
into the silicon nanocrystal physics. A very nice confirmation of this trend is
the k-space projection of the nanocrystal states, which gives a fair explanation
of this phenomenon. Finally, the shape effects on the optical properties
are shown. Several sets of ellipsoidal nanocrystals, with different sizes and
shapes, have been analyzed, and the effects of the geometrical anisotropy on
the polarization of the dielectric tensor is discussed.
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