Materials Science and Engineering B 174 (2010) 182–186 Contents lists available at ScienceDirect Materials Science and Engineering B journal homepage: www.elsevier.com/locate/mseb Physical properties characterization of WO 3 ﬁlms grown by hot-ﬁlament metal oxide deposition J. Díaz-Reyes a,∗ , R.J. Delgado-Macuil a , V. Dorantes-García b , A. Pérez-Benítez c , J.A. Balderas-López d , J.A. Ariza-Ortega a a Centro de Investigación en Biotecnología Aplicada del Instituto Politécnico Nacional, Ex-Hacienda de San Juan Molino, Km. 1.5, Tepetitla, Tlaxcala, 90700, Mexico b Preparatoria “Simón Bolívar” de la Benemérita Universidad Autónoma de Puebla, 4 Oriente 408, Col. Centro, Atlixco, Puebla, C. P. 74200, Mexico c Facultad de Ciencias Químicas de la Benemérita Universidad Autónoma Puebla, 14 Sur y Av. San Claudio, Col. San Manuel, Puebla, Puebla, C. P. 72570, Mexico d Unidad Profesional Interdisciplinaria de Biotecnología del Instituto Politécnico Nacional, Avenida Acueducto S/N, Col. Barrio la Laguna, Ticomán, Del. Gustavo A. Madero, México, D.F. 07340, Mexico article info Article history: Received 2 September 2009 Received in revised form 19 March 2010 Accepted 25 March 2010 Keywords: Compound semiconductors Hot Filament Metal Oxide Deposition Novel Materials and Technological Advances for electrochromics Semiconductors growth WO3 semiconductors abstract WO 3 is grown by hot-ﬁlament metal oxide deposition (HFMOD) technique under atmospheric pressure and an oxygen atmosphere. By X-ray diffraction obtains that WO 3 presents mainly monoclinic crystalline phase. The chemical stoichiometry is obtained by X-ray Photoelectron Spectroscopy (XPS). The IR spec- trum of the as-grown WO 3 presents broad peaks in the range of 1100 to 3600 cm -1 . A broad band in the 2200 to 3600 cm -1 region and the peaks sited at 1645 and 1432 cm -1 are well resolved, which are originated from moisture and are assigned to (OH) and (OH) modes of adsorbed water and the corre- sponding tungsten oxide vibrations are in infrared region from 400 to 1453 cm -1 and around 3492 cm -1 , which correspond to tungsten–oxygen (W–O) stretching, bending and lattice modes. The Raman spec- trum shows intense peaks at 801, 710, 262 and 61 cm -1 that are typical Raman peaks of crystalline WO 3 (m-phase) that correspond to stretching vibrations of the bridging oxygen, which are assigned to W–O stretching () and W–O bending () modes, respectively. By transmittance measurements obtains that the WO 3 band gap can be varied from 2.92 to 3.13 eV in the investigated annealing temperature range. © 2010 Elsevier B.V. All rights reserved. 1. Introduction Metallic oxides are important materials from the standpoint of both fundamental and applied science. Particularly, tungsten and molybdenum oxide ﬁlms have been the focus of extensive scientiﬁc investigations due to their prospective technological applications in electrochromic devices [1], gasochromic sensors [2] and electro- catalysis [3]. However, their most intensively investigated property so far is the electrochromism. The characteristics of WO 3 ﬁlms make them suitable for electrochromic (EC) devices or windows [4]. Depending on the deposition conditions and techniques, ﬁlms may present considerably different structural, optical and elec- trical behaviours, and consequently different EC behaviours. The sputtering technique is the most widely investigated and large- scale deposition set available. Sputtered WO 3 ﬁlms deposited on substrates are known to be amorphous or polycrystalline. Using tungsten (W) targets in direct current (D.C.) magnetron reactive ∗ Corresponding author. E-mail address: jdiazr2001@yahoo.com (J. Díaz-Reyes). sputtering, thin ﬁlm properties can be improved by controlling the reactive gas atmosphere. In recent years, there have been strong development efforts in the area of EC devices because of various potential applications such as architectural glazings, automobile and building sun-roofs, displays for light regulation and energy saving, etc. [5,6]. Elec- trochromic devices have therefore attracted extensive attention among researchers involved in thin ﬁlm preparation [7]. As it is known, the structural quality and components of the material dominate the physical properties of the thin ﬁlms. Both IR and Raman spectroscopy are very powerful tools to analyze the structure, phase and components of materials such as tungsten oxides. They are suitable to study the vibration and rotation of molecules. With these techniques, it is possible not only to iden- tify different oxide phases but also to detect intercalated H 2 O. Such studies allow obtaining fundamental information about WO 3 ﬁlms for their applications. Granqvist had given brief statements about vibrations in the range of 400 to 1200 cm -1 [8]. The Raman vibration mode is related to the molecular structures by compar- ison with standard compound spectra or with Raman theoretical calculations. The use of Raman scattering to study thin ﬁlm has 0921-5107/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.mseb.2010.03.061