348 Optical Properties of WO3 Thin Films

Thursday, November 5, 2009: 2:40 PM
Pancho Villa (Camino Real Hotel)
Satya Kiran Gullapalli , Mechanical Engineering, University of Texas at El paso, El Paso, TX
Ramana Chintalapalle , Mechanical Engineering, University of Texas at El paso, El Paso, TX
Tungsten oxide (WO3) is an interesting material for integration into optical-, electronic- and energy-related devices. WO3 thin films exhibit electrochromism, thermochromism and gaso-chromism and are suitable for use in smart windows, solar panels, gas sensors. The present work was performed on the growth and characterization of WO3 films for sensor-application in advanced energy systems. As a first step, the effect of sputtering-gas pressure on the growth, microstructure and optical properties of WO3 thin films made by RF magnetron sputtering was investigated. A 3 inch W target was used for sputter-deposition of WO3 films. The depositions were made at constant argon pressure with increasing oxygen pressure (pO2) from 1.2 -5.81 mTorr while keeping the substrate temperature constant at 400 C. Optical measurements made using spectrophotometer indicates that optical transmission in WO3 film increases with the increasing pO2. Band gap (Eg) calculations showed the pO2 has a remarkable effect on Eg, which decreased from 3.25 eV to 2.7 eV with increasing pO2. The analyses indicate that stoichiometric WO3 films, which are ideal for use as sensors in advanced energy systems, can be obtained at by tuning pO2. The results obtained will be presented and discussed in detail.