Density-functional and many body perturbation theory calculations have been carried out in order to study the structural, electronic, and opti- cal properties both in ground and excited state configuration, of silicon nanocrystals in different conditions of surface passivation and doping. Starting from hydrogenated clusters, we have considered different Si/O bonding geometries at the interface. We provide strong evidences that not only the quantum confinement effect but also the chemistry at the interface has to be taken into account in order to understand the phys- ical properties of these systems. In particular we show that only the presence of a surface Si-O-Si bridge bond induce an excitonic peak in the emission-related spectra, redshifted with respect to the absorption onset, able to provide an explanation for both the observed Stokes shift and the near-visible photoluminescence (PL) experimentally observed in Si-nc. For the silicon nanocrystals embedded in a SiO2 matrix, the electronic and optical properties are discussed in detail. The strong in- terplay between the nanocrystal and the surrounding host environment and the active role of the interface region between them is pointed out, in very good agreement with the experimental results. Finally, concerning doping, we will show that, thanks to electronic transitions between donor and acceptor states present at the band edges and considering also the effect of quantum confinement it is possible to engineer the absorp- tion and emission spectra of Si nanocrystals. For each considered system optical gain calculations have been carried out giving some insights on the system characteristics necessary to optimize the gain performance of Si-nc.
THEORETICAL STUDIES OF ABSORPTION, EMISSION AND GAIN IN SILICON NANOSTRUCTURES / Degoli, Elena; Guerra, Roberto; Iori, Federico; Magri, Rita; Marri, Ivan; Ossicini, Stefano. - STAMPA. - (2008), pp. 25-60.
|Data di pubblicazione:||2008|
|Titolo:||THEORETICAL STUDIES OF ABSORPTION, EMISSION AND GAIN IN SILICON NANOSTRUCTURES|
|Autore/i:||Degoli, Elena; Guerra, Roberto; Iori, Federico; Magri, Rita; Marri, Ivan; Ossicini, Stefano|
|Codice identificativo Scopus:||2-s2.0-84880188432|
|Titolo del libro:||SILICON NANOPHOTONICS - Basic principles, present status and perspectives|
|A cura di:||Leonid Khriachtchev|
|Editore:||Pan Stanford Publishing|
|Citazione:||THEORETICAL STUDIES OF ABSORPTION, EMISSION AND GAIN IN SILICON NANOSTRUCTURES / Degoli, Elena; Guerra, Roberto; Iori, Federico; Magri, Rita; Marri, Ivan; Ossicini, Stefano. - STAMPA. - (2008), pp. 25-60.|
I documenti presenti in Iris Unimore sono rilasciati con licenza Creative Commons Attribuzione - Non commerciale - Non opere derivate 3.0 Italia, salvo diversa indicazione.
In caso di violazione di copyright, contattare Supporto Iris