Materials Science and Engineering B 174 (2010) 226–230 Contents lists available at ScienceDirect Materials Science and Engineering B journal homepage: www.elsevier.com/locate/mseb Polarization dependent behavior of CdS around the first and second LO-phonon modes C. Frausto-Reyes a,∗ , J.R. Molina-Contreras b,∗ , Y.F. López-Álvarez b , C.I. Medel-Ruíz c , H. Pérez Ladrón de Guevara c , M. Ortiz-Morales a a Centro de Investigaciones en Óptica AC, Unidad Aguascalientes, Prolong., Constitución 607, Fracc. Reserva Loma Bonita, CP 20200, Apartado Postal 507, Ags., Mexico b Departamento de Ingeniería Eléctrica y Electrónica, Instituto Tecnológico de Aguascalientes, Av. López Mateos 1081 Oriente, Fracc. Bonna Gens, CP 20256, Aguascalientes, Ags., Mexico c Universidad de Guadalajara, Centro Universitario de los Lagos, Av. Enrique Díaz de León s/n, Fracc. Paseos de la Monta˜ na, CP 47460, Lagos de Moreno, Jal., Mexico article info Article history: Received 24 August 2009 Received in revised form 24 March 2010 Accepted 29 March 2010 Keywords: Cadmium sulphide Raman spectroscopy Polarization effects Resonant effects Surface roughness abstract The present work report studies on resonant Raman experimental line shape for CdS around the first and second LO-phonon modes. The application of our method to the study of LO-phonon modes of CdS suggests that the scattered intensity is dominated by the surface and dependent on polarization. Results showed that the Raman spectra for CdS, roughly fall into three groups: a broad line-wing with apparent maxima around 194 cm -1 in the range of 140 and 240 cm -1 which can be ascribed to overtone scattering from acoustic phonons; a band near the 1LO phonon mode which can be attributed to a combination of one-phonon scattering and peak acoustic phonon and finally, a band near the 2LO phonon mode which can be attributed to a combination of two-phonon scattering and peak acoustic phonon. © 2010 Elsevier B.V. All rights reserved. 1. Introduction Wide band gap semiconductors are promising materials for versatile applications in ultra-violet optoelectronics, electro-optic and acousto-optic devices among others due the combination of their outstanding performances and various physical properties. The range of applications of the II–VI semiconductors however is strongly dependent on their behavior. The development in variable polarization technique has resulted in several important contributions. From a classical treatment point of view, the intensity of the radiation, calculated from time aver- aged power radiated by the induced polarizations into unit solid angle, will be proportional to [1] I s ∝   e i · (∂/∂Q ) 0 ˆ Q (w 0 ) · e s   2 , (1) where I s is the scattered radiation, e i is the polarization of the incident radiation. (∂/∂Q ) 0 ˆ Q (w 0 ) represents an oscillating sus- ceptibility induced by the lattice wave Q(r, t) and e s is the polarization of the scattered radiation. Germer et al. [2,3] have shown that light scattered by a sample has a polarization dependent component upon the nature of the ∗ Corresponding author. Tel.: +52 (449) 4428124; fax: +52 (449) 4428127. E-mail addresses: cfraus@cio.mx (C. Frausto-Reyes), rmolina@correo.ita.mx (J.R. Molina-Contreras). scattering source when a p-polarized light is incident at an oblique angle. Martin and Damen [4], showed that the enhancement in the LO phonon in the allowed scattering configuration for CdS was weaker than those in the forbidden geometries. They also sug- gested a breakdown of the Loudon selection rules for LO phonons at resonance. Resonant Raman can be used to study interband electronic tran- sitions, excitations and even electron–phonon interactions. Due to this, Raman scattering is one of the most versatile spectroscopic techniques for studying not only semiconductors but also other condensed media [1]. In this paper, we report Raman study of the polarization depen- dent behavior of CdS around the first and second LO-phonon modes. Raman spectra for CdS, have three different intensity profiles a broad line-wing with apparent maxima around 194 cm -1 in the range of 140 and 240 cm -1 which can be ascribed to overtone scat- tering from acoustic phonons; a band near the 1LO phonon mode which can be attributed to a combination of one-phonon scattering and peak acoustic phonon and finally, a band near the 2LO phonon mode which can be attributed to a combination of two-phonon scattering and peak acoustic phonon. Results also suggest that the Raman spectra experiment dependent on polarization of incident light and roughness of the sample. Raman spectra for positive and negative polarization relating the scattered and incident radiation are discussed. 0921-5107/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.mseb.2010.03.073