Study of optical phonon modes of CdS nanoparticles using Raman spectroscopy
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The reduction in the grain size to nanometer range can bring about radical changes in almost all of the properties of semiconductors. CdS nanoparticles have attracted considerable scientific interest because they exhibit strongly size-dependent optical and electrical properties. In the case of nanostructured materials, confinement of optical phonons can produce noticeable changes in their vibrational spectra compared to those of bulk crystals. In this paper we report the study of optical phonon modes of nanoparticles of CdS using Raman spectroscopy. Nanoparticle sample for the present study was synthesized through chemical precipitation technique. The CdS nanoparticles were then subjected to heat treatment at low temperature (150°C) for extended time intervals. The crystal structure and grain size of the samples were determined using X-ray diffraction and HRTEM. The Raman spectra of the as-prepared and heat treated samples were recorded using conventional Raman and micro-Raman techniques. The spectrum of as prepared sample exhibited an intense, broad peak at 301 cm−1 corresponding to the LO phonon mode. Higher order phonon modes were also observed in the spectra. A noticeable asymmetry in the Raman line shape indicated the effect of phonon confinement. Other features in the spectra are discussed in detail.
KeywordsNanoparticles optical phonons cadmium sulfide Raman
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- Abdi A, Titova L V, Smith L M, Jackson H E, Rice J M Y, Lensch J L and Lauhon L J 2006 Appl. Phys. Lett. 88 043118Google Scholar
- Arora A K, Rajalakshmi M and Ravindran T R 2004 in Encyclopedia of nanoscience and technology (ed.) H S Nalwa (Los Angeles: American Scientific Publishers) Vol. 8, p. 499Google Scholar
- Bischof T, Lermann G, Schreder B, Materny A, Kiefer W and Ivanda M 1997 J. Opt. Soc. Am. B14 3334Google Scholar
- Cullity B D and Stock S R 2001 Elements of X-ray diffraction (New York: Prentice Hall Publishers) 3rd ed., p. 664Google Scholar
- Chuu D R and Dai C M 1992 Phys. Rev. B45 11805Google Scholar
- Nemanich J, Solin S A and Martin R M 1981 Phys. Rev. B23 6348Google Scholar
- Nandakumar P, Vijayan C, Rajalakshmi M, Arora A K and Murti Y V G S 2001 Physica E11 377Google Scholar
- Roy A and Sood A K 1996 Phys. Rev. B53 12127Google Scholar
- Sivasubramanian V, Arora A K, Premila M, Sundar C S and Sastry V S 2006 Physica E31 93Google Scholar