AVS 56th International Symposium & Exhibition
    Thin Film Wednesday Sessions
       Session TF-WeA

Paper TF-WeA3
Tungsten Oxide (WO3) Thin Films for Application in Advanced Energy Systems

Wednesday, November 11, 2009, 2:40 pm, Room B4

Session: ALD/CVD: Novel Applications, Mechanical Properties
Presenter: S.K. Gullapalli, University of Texas at El Paso
Authors: S.K. Gullapalli, University of Texas at El Paso
C.V. Ramana, University of Texas at El Paso
Correspondent: Click to Email
Coal gasification plants are advanced energy production systems. Inherent processes in these plants produce a lot of hazardous gases, such as hydrogen sulfide (H2S), which must be continuously and efficiently detected and removed before the syngas is used for power generation. The objective of the present work is to develop stable and reliable H2S sensors based on nanostructured tungsten oxide (WO3) thin films. The chemical sensing ability and high-temperature stability of WO3 is the motivation for the work. WO3 thin films have been fabricated by RF reactive magnetron-sputter deposition. A W-target has been employed for all the depositions and to investigate the effect of processing conditions on the growth and structure of resulting WO3 films. The fabrication has been made under varying substrate temperatures (Ts), in the range 30(RT)-400 oC. The argon to oxygen flow ratio is kept constant at 1:6 for reactive deposition and oxide formation. Investigations made using x-ray diffraction (XRD) and scanning electron microscopy (SEM) indicate that the effect of Ts is significant on the microstructure of WO3 films. XRD and SEM results indicate that the WO3-films grown RT are amorphous, whereas films grown at higher temperatures are nanocrystalline. Thermally activated growth process of WO3 films is evident in the data. The average grain size increases with increasing Ts. WO3 films exhibit smooth morphology at lower temperatures (< 200 oC) while relatively rough at 400 oC. The optical measurements indicate that the films exhibit relatively high transmittance and the band gap is dependent on the grain-size. The analyses indicate that the nanocrystalline WO3 films grown at 100-200 oC could be the potential candidates for H2S sensor development for application in coal gasification systems.