TY - JOUR
KW - paper
AU - Federico Iori
AU - Elena Degoli
AU - R Magri
AU - Ivan Marri
AU - G. Cantele
AU - D. Ninno
AU - Fabio Trani
AU - Olivia Pulci
AU - Stefano Ossicini
AB - We show that the optical and electronic properties of nanocrystalline silicon can be efficiently tuned using impurity doping. In particular, we give evidence, by means of ab initio calculations, that by properly controlling the doping with either one or two atomic species, a significant modification of both the absorption and the emission of light can be achieved. We have considered impurities, either boron or phosphorous (doping) or both (codoping), located at different substitutional sites of silicon nanocrystals with size ranging from 1.1 to 1.8 nm in diameter. We have found that the codoped nanocrystals have the lowest impurity formation energies when the two impurities occupy nearest neighbor sites near the surface. In addition, such systems present band-edge states localized on the impurities, giving rise to a redshift of the absorption thresholds with respect to that of undoped nanocrystals. Our detailed theoretical analysis shows that the creation of an electron-hole pair due to light absorption determines a geometry distortion that, in turn, results in a Stokes shift between adsorption and emission spectra. In order to give a deeper insight into this effect, in one case we have calculated the absorption and emission spectra beyond the single-particle approach, showing the important role played by many-body effects. The entire set of results we have collected in this work give a strong indication that with the doping it is possible to tune the optical properties of silicon nanocrystals.
BT - PHYSICAL REVIEW B
CY - ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA
DA - AUG
DO - 10.1103/PhysRevB.76.085302
M1 - 8
N2 - We show that the optical and electronic properties of nanocrystalline silicon can be efficiently tuned using impurity doping. In particular, we give evidence, by means of ab initio calculations, that by properly controlling the doping with either one or two atomic species, a significant modification of both the absorption and the emission of light can be achieved. We have considered impurities, either boron or phosphorous (doping) or both (codoping), located at different substitutional sites of silicon nanocrystals with size ranging from 1.1 to 1.8 nm in diameter. We have found that the codoped nanocrystals have the lowest impurity formation energies when the two impurities occupy nearest neighbor sites near the surface. In addition, such systems present band-edge states localized on the impurities, giving rise to a redshift of the absorption thresholds with respect to that of undoped nanocrystals. Our detailed theoretical analysis shows that the creation of an electron-hole pair due to light absorption determines a geometry distortion that, in turn, results in a Stokes shift between adsorption and emission spectra. In order to give a deeper insight into this effect, in one case we have calculated the absorption and emission spectra beyond the single-particle approach, showing the important role played by many-body effects. The entire set of results we have collected in this work give a strong indication that with the doping it is possible to tune the optical properties of silicon nanocrystals.
PB - AMER PHYSICAL SOC
PP - ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA
PY - 2007
T2 - PHYSICAL REVIEW B
TI - Engineering silicon nanocrystals: Theoretical study of the effect of codoping with boron and phosphorus
UR - http://dx.doi.org/10.1103/PhysRevB.76.085302
VL - 76
ER -