Synthesis of Tungsten Trioxide Thin Films for Gas Detection

  • Author / Creator
    Murray, Andrew John
  • The ability to detect and quantify presence and concentration of unknown gasses is sought for applications ranging from environmental monitoring to medical analysis. Metal oxide based chemical sensing technology currently exists but the ability to provide a compositional gas breakdown reliably within a short time frame is not readily available. A very small sensor that can differentially identify the type and concentration of a gas is required. Novel methods of creating low cost and easily tuned one and two-dimensional gas sensing elements are explored. Tungsten trioxide has been thoroughly documented as an electrochromic coating, but highly sensitive WO3 elements with beam and nanowire structures have yet to be explored. Research of WO3 as a gas sensor encompasses three major components: A suitable sensing chamber with accurate analyte gas flow control and temperature control, a reliable method for WO3 deposition, and a high yield fabrication process. This thesis explores all three of these technologies. Chapter two starts with a summary of existing tungsten trioxide fabrication methods. An overview of WO3 processing follows. A comprehensive setup was designed and created to test the gas sensing response of a series of metal oxide based resistive elements through conductimetric analysis. Chapter three provides an in depth account of gas sensor test chamber design and testing. Critical test chamber aspects such as temperature control, precise gas flow control, highly efficient analyte gas switching and ease of use are presented. Chapter four outlines WO3 electrodeposition and the fabrication of beam structures for testing, while chapter five explores the templated electrodeposition of WO3 segments intercalated between gold nanowire segments. Finally, chapter six provides a summary of the research presented in this thesis as well as future directions and options available for further exploration of WO3 gas sensing elements.

  • Subjects / Keywords
  • Graduation date
    Spring 2010
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.