Radiative exciton recombination and defect luminescence observed in single silicon nanocrystals
2012 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 86, no 12, 125302- p.Article in journal (Refereed) Published
The role of quantum confinement (QC) and surface-related defect centers (DCs) on the photoluminescence (PL) of individual silicon nanocrystals (Si NCs) is investigated using confocal microscopy with radially and azimuthally polarized laser beams. It is shown that the multiple-peak PL spectra of single Si NCs revealing SiO 2 phonon side bands are associated with a linear transition dipole moment (TDM) and a short lifetime of 4 ns, indicating that the PL originates from defect centers. In a new study applied to free-standing single Si NCs obtained by Si cluster beam deposition, we could discriminate between PL centers with one- and more-dimensional TDM. Nanoparticles revealing a three-dimensional TDM are characterized by a significantly weaker and structureless Gaussian PL band at larger wavelengths and by ÎŒs lifetimes. These PL features are attributed to the radiative recombination of quantum-confined excitons generated in the Si cores. Within the same sample, we found coexistence of Si NCs exhibiting QC PL and others showing DC PL.
Place, publisher, year, edition, pages
2012. Vol. 86, no 12, 125302- p.
IdentifiersURN: urn:nbn:se:kth:diva-103659DOI: 10.1103/PhysRevB.86.125302ISI: 000308288700008ScopusID: 2-s2.0-84866396841OAI: oai:DiVA.org:kth-103659DiVA: diva2:561216
QC 201210172012-10-172012-10-172012-10-17Bibliographically approved