New approaches for improving semiconductor gas sensors

https://doi.org/10.1016/0925-4005(91)80213-4Get rights and content

Abstract

It is demonstrated that the sensing characteristics of a semiconductor gas sensor using SnO2 can be improved by controlling fundamental factors which affect its receptor and transducer functions. The transducer function is deeply related with the microstructure of the elements, i.e., the grain size of SnO2 (D) and the depth of the surface space-charge layer (L). The sensitivity is drastically promoted when D is made comparable to or less than 2L, either by control of D for pure SnO2 elements or by control of the Debye length for impurity-doped elements. On the other hand, the receptor function is drastically modified by the introduction of foreign receptors on the surface of SnO2. In the particular cases of Pd and Ag promoters, the oxides (PdO and Ag2O) formed in air interact with the SnO2 surface to produce an electron-deficient space-charge layer, and this contributes much to promoting the gas sensitivity. For a test gas having a specific reactivity, such specificity can be utilized for exploiting gas-selective receptors, as exemplified by CuOSnO2 and La2O3SnO2 elements, which detect H2S and ethanol gas respectively very sensitively.

References (40)

  • P.J. Shaver

    Activated tungsten oxide gas detectors

    Appl. Phys. Lett.

    (1967)
  • S. Kanefusa et al.

    Thick film gas leak detector for town gas

    J. Chem. Soc. Jpn.

    (1980)
  • Y. Okayama et al.

    SnO2PdSb hydrogen gas sensor nonsensitive to alcohol

    Denki Kagaku

    (1986)
  • J.F. McAleer et al.

    Tin dioxide gas sensors part 1, Aspects of the surface chemistry revealed by electrical conductance variation

    J. Chem. Soc.

    (1987)
  • S. Matsushima et al.

    Electronic interaction between metal additives and tin dioxide in tin dioxide-based gas sensors

    Jpn. J. Appl. Phys.

    (1988)
  • J.F. McAleer et al.

    Tin dioxide gas sensors part 2, The role of surface additives

    J. Chem. Soc.

    (1988)
  • T. Nakahara, K. Takahata and S. Matsuura, High sensitive SnO2 gas sensor, I. Detection of volatile sulphides, Proc....
  • Y. Shimizu et al.

    Detection of freshness of fish by a semiconductive Ru/TiO2 sensor

    J. Electrochem. Soc.

    (1988)
  • T. Takada and K. Komatsu, O3 gas sensor of thin film semiconductor In2O3, Proc. 4th Int. Conf. Solid-State Sensors and...
  • T. Seiyama et al.

    Gas detection by activated semiconductive sensor

    Denki Kagaku

    (1972)
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