## 抄録

Influences of gas transport phenomena on the sensitivity of a thin film semiconductor gas sensor were investigated theoretically. A diffusion equation was formulated by assuming that an inflammable gas (target gas) moves inside the film by Knudsen diffusion, while it reacts with the adsorbed oxygen following a first-order reaction kinetic. By solving this equation under steady-state conditions, the target gas concentration inside the film was derived as a function of depth (x) from the film surface, Knudsen diffusion coefficient (D_{K}), rate constant (k) and film thickness (L). The gas concentration profile thus obtained allowed to estimate the gas sensitivity (S) defined as the resistance ratio (R_{a}/R_{g}), under the assumption that the sheet conductance of the film at depth x is linear to the gas concentration there with a proportionality constant (sensitivity coefficient), a. The derived equation shows that S decreases sigmoidally down to unity with an increase in L√k/D_{K}. Further by assuming that the temperature dependence of rate constant (k) and sensitivity coefficient (a) follows Arrenius type ones with respective activation energies, it was possible to derive a general expression of S involving temperature (T). The expression shows that, when the activation energies are selected properly, the S versus T correlation results in a volcano-shaped one, its height increasing with decreasing L. The dependence of S on L at constant T as well as on T at constant L can thus be simulated fairly well based on the equation.

本文言語 | 英語 |
---|---|

ページ（範囲） | 125-131 |

ページ数 | 7 |

ジャーナル | Sensors and Actuators, B: Chemical |

巻 | 80 |

号 | 2 |

DOI | |

出版ステータス | 出版済み - 11 20 2001 |

## All Science Journal Classification (ASJC) codes

- Electronic, Optical and Magnetic Materials
- Instrumentation
- Condensed Matter Physics
- Surfaces, Coatings and Films
- Metals and Alloys
- Electrical and Electronic Engineering
- Materials Chemistry