Structural interpretation of the infrared spectrum of a Sb0.05As0.45Se0.50glassy semiconductor

The infrared (IR) absorption spectrum for glassy Sb0.05As0.45Se0.50 was mea sured in the wave number region 500-90 cm(-1) at room temperature and in a continuously purged sample compartment, following the polyethylene pellet m ethod. Main structural units in the glassy are considered to be AsSe3 and S bSe3 pyramids, Se-8 rings and Se-n chains. By using X-ray diffraction data it was found a structural model with the assumption of tricoordinated As, t ricoordinated Sb and dicoordinated Se [C. Corredor, J. Vazquez, R.A. Ligero , P. Villares, R. Jimenez-Garay, Materials Letters 36, 1998, 271; I. Quirog a, J. Vazquez,P. Villares, R. Jimenez-Garay, :Materials Letters 17, 1993, 3 33.] which confirms the information obtained by means of far-infrared trans mission (I;IT). From the "Valence Force Field" (VFF) we can determine the v ibrational frequencies, wi, of possible structural units of alloy in this s tudy by using the expressions derived by Herzberg. The results for this all oy are the following: 85, 110 and 230 cm(-1), for AsSe3, and 112, 215 and 3 15 cm(-1), for SbSe3. The comparison between the frequencies obtained in th e far-IR spectrum and the values calculated of the normal frequencies let u s assign bands to structural units. (C) 2000 Elsevier Science B.V. All righ ts reserved.