Dielectric function and optical transitions of silicon nanocrystals between 0.6 eV and 6.5 eV

• Published in: Physica status solidi. A, Applications and materials science Applications and materials science, 2008-04, Vol.205 (4), p.845-848
• Main Authors: Mansour, M., En Naciri, A., Johann, L., Grob, J. J., Stchakovsky, M.
• Format: Article
• Language: English
• Subjects: 78.20.Bh; 78.20.Ci; 78.67.Bf; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Nanocrystals and nanoparticles; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures; Physics
• ISSN: 1862-6300; 0031-8965; 1862-6319
• DOI: 10.1002/pssa.200777762

In this work, we report on the study of the dielectric function of nanocrystal silicon (nc‐Si) implanted in a SiO2 matrix on a silicon substrate by spectroscopic ellipsometry (SE). The formed nc‐Si have an average size around 4 nm. The SE measurements are performed at an angle of incidence of 70° in air at room temperature and in the spectral range of 0.6 eV to 6.5 eV. Two models are used to extract the optical responses of nc‐Si: Forouhi–Bloomer formalism and wavelength‐by‐wavelength inversion. The nc‐Si exhibits a significant reduction in the dielectric functions in comparison with the bulk Si. We have observed a reduction of the amplitude of the E1 transition with a very weak shift of its energy position. The transition E2 is characterized by a rather broad peak with an amplitude greater than that of E1. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)