Structural and CO sensing characteristics of Ti-added SnO 2 thin films

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Abstract

Thin films of SnO 2 with Ti additives were deposited on silicon wafers by co-sputtering from a Sn and a Ti metal targets in an Ar + O 2 mixture. The Ti contents of the films were controlled by the d.c. power (10-90 W) applied on Ti target. All SnO 2 -Ti films were annealed in flowing oxygen at 900 °C for 5 h. The phases, composition, microstructure and chemical bonding states of the SnO 2 -Ti films were examined. Resistances of the SnO 2 -Ti samples under the atmosphere of various CO concentrations (1500-2500 ppm) were measured to determine the gas sensitivity. As-deposited SnO 2 -Ti films are amorphous and exhibit zero sensitivity to CO gas. SnO 2 -Ti films transformed to polycrystalline structure of rutile SnO 2 phase after annealing at 900 °C. The quantity of Ti additives increases with increasing sputtering power on Ti. In the mean time, the Sn concentration decreases with increasing Ti, which results in the reduction of oxygen vacancies in the films. Sensitivity measurements on the annealed SnO 2 -Ti films reveal that the SnO 2 -Ti film prepared with 50 W of d.c. power on Ti target has the highest sensitivity to CO. The effects of Ti additives on the material characteristics and sensing properties of SnO 2 -Ti films are discussed.

Original languageEnglish
Pages (from-to)305-312
Number of pages8
JournalApplied Surface Science
Volume187
Issue number3-4
DOIs
Publication statusPublished - 2002 Feb 28

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Surfaces and Interfaces

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