Transworld Research Network 37/661 (2), Fort P.O. Trivandrum-695 023 Kerala, India Thermal Wave Physics and Related Photothermal Techniques: Basic Principles and Recent Developments, 2009: 159-190 ISBN: 978-81-7895-401-1 Editor: Ernesto Marín Moares 6. Characterization of semiconductors using photoacoustics E. Marín 1 , A. Calderón 1 and I. Riech 2 1 Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Legaria 694 Colonia Irrigación C.P. 11500, México D.F., México; 2 Facultad de Ingeniería Universidad Autónoma de Yucatán, Apdo. Postal 150 Cordemex Mérida, Yucatán, México Abstract. Since the early seventies, photoacoustic has been emerged as a well suited technique for the measurement of optical and transport properties of semiconductors, showing in many cases considerable advantages respecting other characterization methods. As these materials are often grown in the form of thin films on different kind of substrates, in this chapter we shall describe some of the theoretical models devised in the last years to the measurement of their electronic transport properties. We will also show how photoacoustic spectroscopy allows the measurement of the wavelength dependence of the optical absorption coefficient of very opaque semiconductor thin layers. 1. Introduction Since the later fifties the field of semiconductors has become an enormous impact in society and global economy because semiconductor devices are the basis of some of the largest industries in the world, namely the micro- and optoelectronic industries, as well as of those depending on their products. One Correspondence/Reprint request: Dr. E. Marín, Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada Legaria 694, Colonia Irrigación, C.P. 11500, México D.F., México. E-mail: emarinm@ipn.mx