Engineering light absorption by switching co-doping in SiGe coreshell nanowires
Michele Amato (1,2), Maurizia Palummo (3), Riccardo Rurali (4) and Stefano Ossicini (5,6)
(1) Laboratoire des Solides Irradiés, École Polytechnique, 91128 Palaiseau, France
(2) Université Paris Sud, Laboratoire de Physiques des Solides, 91405 Orsay, France
(3) Dipartimento di Fisica, European Theoretical Spectroscopy Facility (ETSF), Università di Roma,
Tor Vergata, Via della Ricerca Scientifica 1, 00133 Roma, Italy
(4) Institut de Ciència de Materials de Barcelona (CSIC), Campus de Bellaterra, 08193 Bellaterra,
Barcelona, Spain
(5) Dipartimento di Scienze e Metodi dell’Ingegneria, Università di Modena e Reggio Emilia, Via
Amendola 2 Pad. Morselli, I-42100 Reggie Emilia, Italy
(6) Centro Interdepartmental En&Tech, Università di Modena e Reggie Emilia, Via Amendola 2 Pad.
Morselli, I-42100 Reggio Emilia, Italy
Tuning the electronic and optical features of materials through size reduction [1],
alloying [2, 3] and doping [4] can pave the way to very exciting device applications, in
particular in the field of photovoltaics [5]. By means of ab-initio calculations in the
framework of Density Functional Theory we investigate the structural, electronic and
optical properties of codoped SiGe core-shell nanowires [6]. We show how the
simultaneous addition of impurities results in a gain of energy with respect to the
single-doping cases. Moreover we demonstrate how the Si/Ge band offset and the
impurity position into the wire can strongly modify the energetic levels of dopants
into the band-gap. This electronic tunability reflects into a strong modulation of the
optical absorption spectra when positions of dopants are switched, suggesting a
promising way to engineering light absorption in nanostructures.
References:
[1] R. Rurali, Rev. Mod. Phys. 82, 427–449 (2010)
[2] J.-E. Yang et al., Nano Lett. 6 (12), 2679–2684 (2006)
[3] J. Xiang et al., Nature 441, 489-493 (2006)
[4] Y. Cui et al., J. Phys. Chem. B, 104 (22), 5213–5216 (2000)
[5] K.-Q. Peng and S.-T. Lee, Adv. Mater. 23, 2, 198–215 (2011)
[6] M. Amato, M. Palummo, R. Rurali and S. Ossicini (to be submitted) (2012)