The absorption and, for the first time, the emission spectra of doped silicon nanocrystals have been calculated within a first-principles framework including geometry optimization. Starting from hydrogenated silicon nanocrystals, simultaneous n- and p-type doping with boron and phosphorous impurities have been considered. We found that the B–P co-doping results to be easier than simple B- or P-doping and that the two impurities tend to occupy nearest neighbours sites inside the nanocrystal itself. The co-doped nanocrystals bandstructure presents band edge states that are localized on the impurities and are responsible of the red-shifted absorption threshold with respect to that of pure un-doped nanocrystals in fair agreement with the experimental outcome. The emission spectra show a Stokes shift with respect to the absorption due to the structural relaxation after the creation of the electron–hole pair. Moreover, the absorption and emission spectra have been calculated for a small co-doped nanocrystal beyond the single particle approach by introducing the selfenergycorrection and solving the Bethe–Salpeter equation scheme. Our procedure shows the important role played by the many-bodyeffects.

Doping in silicon nanocrystals / Ossicini, Stefano; Degoli, Elena; F., Iori; O., Pulci; G., Cantele; Magri, Rita; Bisi, Olmes; F., Trani; D., Ninno. - In: SURFACE SCIENCE. - ISSN 0039-6028. - STAMPA. - 601:13(2007), pp. 2724-2729. [10.1016/j.susc.2006.12.083]

Doping in silicon nanocrystals

OSSICINI, Stefano;DEGOLI, Elena;MAGRI, Rita;BISI, Olmes;
2007

Abstract

The absorption and, for the first time, the emission spectra of doped silicon nanocrystals have been calculated within a first-principles framework including geometry optimization. Starting from hydrogenated silicon nanocrystals, simultaneous n- and p-type doping with boron and phosphorous impurities have been considered. We found that the B–P co-doping results to be easier than simple B- or P-doping and that the two impurities tend to occupy nearest neighbours sites inside the nanocrystal itself. The co-doped nanocrystals bandstructure presents band edge states that are localized on the impurities and are responsible of the red-shifted absorption threshold with respect to that of pure un-doped nanocrystals in fair agreement with the experimental outcome. The emission spectra show a Stokes shift with respect to the absorption due to the structural relaxation after the creation of the electron–hole pair. Moreover, the absorption and emission spectra have been calculated for a small co-doped nanocrystal beyond the single particle approach by introducing the selfenergycorrection and solving the Bethe–Salpeter equation scheme. Our procedure shows the important role played by the many-bodyeffects.
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Doping in silicon nanocrystals / Ossicini, Stefano; Degoli, Elena; F., Iori; O., Pulci; G., Cantele; Magri, Rita; Bisi, Olmes; F., Trani; D., Ninno. - In: SURFACE SCIENCE. - ISSN 0039-6028. - STAMPA. - 601:13(2007), pp. 2724-2729. [10.1016/j.susc.2006.12.083]
Ossicini, Stefano; Degoli, Elena; F., Iori; O., Pulci; G., Cantele; Magri, Rita; Bisi, Olmes; F., Trani; D., Ninno
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11380/615127
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