Solar Energy Materials & Solar Cells 90 (2006) 704–712 Photoluminescence studies of CdS thin films annealed in CdCl 2 atmosphere J. Aguilar-Herna´ndez à , J. Sastre´-Herna´ndez, R. Mendoza-Pe´rez, G. Contreras-Puente, M. Ca´rdenas-Garcı´a, J. Ortiz-Lo´pez Escuela Superior de Fı´sica y Matema´ticas, Instituto Polite´cnico Nacional, Edificio No. 9 U.P.A.L.M. Lindavista C.P. 07738, Me´xico D.F. Available online 23 May 2005 Abstract We have grown CdS films by the Close Spaced Vapor Transport technique under specific conditions: substrate temperature (T s ): 450 1C, source temperature (T so ): 725 1C, argon pressure in the chamber (P Ar ): 100, 200 and 500 mT, deposition time (t d ): 100 s. The films were studied by measuring the luminescence properties at different temperatures in the range 10–300 K. The room-temperature PL spectrum of the as-grown CdS films showed a very broad band centered at 2.26 eV and a shoulder in the low-energy side at 1.80 eV. After CdCl 2 thermal annealing at 300 K, the spectrum showed better PL characteristics: a strong band in the low- energy side at 1.67 eV and a band in the high-energy side at 2.47 eV. The analysis at lower temperatures showed that the high-energy band becomes most intense and shifts to higher energies reaching a value of 2.54 eV, very close to the energy band gap at 10 K. The low-energy band becomes broader and centered around 1.9 eV. Analysis of the PL intensity as a function of temperature in an Arrhenius representation, allows applying a theoretical model for the quenching of the PL intensity. r 2005 Elsevier B.V. All rights reserved. Keywords: CdS; Photoluminescence; Exciton band; CdCl 2 ; Temperature dependence ARTICLE IN PRESS www.elsevier.com/locate/solmat 0927-0248/$ - see front matter r 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.solmat.2005.04.007 à Corresponding author. Tel.: +52 57296139; fax: +52 55862957. E-mail address: jaguilar@esfm.ipn.mx (J. Aguilar-Herna´ndez).