reprint
pss
Phys. Status Solidi RRL 5, No. 7, 250– 252 (2011) / DOI 10.1002/pssr.201105219
Vibrational Raman spectra of CdSxSe1–x magic-size nanocrystals
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Volodymyr Dzhagan*, 1, Nikolai Mel’nik2, Olexandra Rayevska3, Galyna Grozdyuk3, Viktor Strelchuk1, Olga Plyashechnik2, Stepan Kuchmii3, and Mykhailo Valakh**,1 1
V.Ye. Lashkaryov Institute of Semiconductor Physics of Natl. Acad. Sci. of Ukraine, Prospekt Nauky 45, 03028 Kyiv, Ukraine P. N. Lebedev Physical Institute, Russian Academy of Sciences, Leninsky Prosp. 53, 119991 Moscow, Russian Federation 3 L.V. Pysarzhevskiy Institute of Physical Chemistry of Natl. Acad. Sci. of Ukraine, Prospekt Nauky 31, 03028 Kyiv, Ukraine 2
Received 4 May 2011, revised 1 June 2011, accepted 6 June 2011 Published online 14 June 2011 Keywords Raman spectra, phonons, CdS, CdSSe, nanocrystals ** **
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[email protected], Phone: +38 044 525 8550, Fax: +38 044 525 8550
Resonant Raman scattering spectra of ultrasmall (< 2 nm) magic-size nanocrystals (NCs) are reported. The spectra of CdS and CdSxSe1–x NCs, resonantly excited with 325 nm and 442 nm laser lines, correspondingly, reveal broad features in the range of bulk optical phonons. The relatively large width,
~ 50 cm–1, and downward shift, ~ 20 cm–1, of the Raman bands with respect to the longitudinal optical phonon in bulk crystals and large NCs are discussed based on the breaking of the translational symmetry and bond distortion in these ultrasmall NCs.
© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
1 Introduction The magic-size semiconductor nanocrystals (MSNCs) have recently attracted much attention due to their unique physical properties [1–6]. Their strong broad-band luminescence has been recently reported [3, 7] and studied as a promising source of white emission [1, 4, 8–10]. The structure and properties of this kind of nanostructures need, however, a deeper understanding. Here we report on Raman scattering on lattice vibrations in ultrasmall (
