Metal-Semiconductor Contacts for Sensor Application

用于传感器应用的金属-半导体触点

• 批准号: 01460138
• 负责人: ITO Kentaro
• 金额: $ 4.22万
• 依托单位: Shinshu University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (B)
• 财政年份: 1989
• 资助国家: 日本
• 起止时间: 1989 至 1991
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-01460138/
• 关键词: anodization; semiconducting oxide; hydrated tungsten oxide; metal-semiconductor contacts; hydrogen sensor; PTC effect; 水和酸化タングステン; 着色機構; 陽極酸化膜; 同位体効果; 反射率; 水素タングステンブロンズ; プロトンの拡散; 応答時間; 酸化物半導体; 酸化タングステン; 水素クロミズム; 光学密度; 凝結水; Pd薄膜; 金属-半導体

We have investigated metal-semiconducting oxide contacts to develop a highly selective and sensitive hydrogen detector and a positive temperature coefficient (PTC) thermistor. Our purpose in this research is to elucidate fundamental mechanisms for these sensors and optimize process parameters of the device fabrications.We have found that a forward current of the diode consisting of Pd thin film and semiconducting Sr_xBa_<1-x>TiO_3 ceramics increases on exposure to hydrogen. The barrier height depends on hydrogen concentration in the same way as that of a Pd MOS structure. The reverse currents of Au/anodic oxide/ barium strontium titanate ceramics structure shows the PTC effect and voltage dependence which follows the Fowler-Nordheim equation.A transmission-type hydrogen sensor is fabricated by using a sputtered amorphous tungsten oxide film which is deposited on the glass substrate and then covered with semitransparent Pd thin film. A decrease in the spectral transmittance by hydrogen has a peak at the wavelength of 900 nm. The response time of the sensor is of the order of 10^2 s. Though the hydrogen sensitivity is considerably degraded after annealing at 200 ﾟC in vacuum, the sensor partially recovers the initial response time after subsequent exposure to water vapor at 100 ﾟC and aging in room air.A reflection-type hydrogen sensor consists of an anodic oxide film formed on the W sheet and then covered with semitransparent Pd or Pt film. Its response time is of the order of 10 s. It is revealed by X-ray diffraction that the film consists of WO^3・H^2O. Coloration mechanism for the sensor is considered to be based on formation of hydrogen tungsten bronzes and a consequent increase in electron concentration of the film. A rate determining step of the coloration reaction is probably due to water-assisted proton diffusion. The best processes for polishing and anodizing the W sheet are also presented.

我们已经研究了金属半导体氧化物接触，以开发高选择性和灵敏度的氢检测器和正温度系数（PTC）热敏电阻。我们的研究目的是阐明这些传感器的基本机制和优化的工艺参数的器件制造。我们发现，由Pd薄膜和半导体Sr_xBa_TiO_3陶瓷组成的二极管的正向电流<1-x>增加暴露于氢。势垒高度以与Pd MOS结构相同的方式取决于氢浓度。Au/阳极氧化物/钛酸锶钡陶瓷结构的反向电流表现出PTC效应，并遵循Fowler-Nordheim方程，采用溅射法在玻璃衬底上沉积非晶氧化钨薄膜，然后在其上覆盖一层不透明的Pd薄膜，制成了透射式氢传感器。氢引起的光谱透射率的降低在900 nm的波长处具有峰值。传感器的响应时间为10^2 s。在200 ℃真空退火后，氢敏性能明显下降，但在100 ℃水蒸气中暴露和室温老化后，传感器的初始响应时间可部分恢复。其响应时间为10 s量级。X射线衍射分析表明，薄膜由WO^3·H^2O组成。传感器的着色机理被认为是基于氢钨青铜的形成和随之而来的膜的电子浓度的增加。显色反应的速率决定步骤可能是由于水辅助质子扩散。提出了钨片抛光和阳极氧化的最佳工艺。

项目成果

K. Takahashi and K. Ito.: "Principles od Sensors" The Institute of Electrical Engineers of Japan. 1-215 (1990)

K. Takahashi 和 K. Ito.：“传感器原理”日本电气工程师协会。

高橋 清: "基礎センサ工学" 電気学会, 215 (1990)

高桥清：《传感器工程基础》日本电气工程师学会，215（1990）

K.Ito,T.Ohgami,T.Nakazawa: "Effect of water on hydrogen-sensitive tungsten oxide films" Sensors and Actuators.

K.Ito、T.Ohgami、T.Nakazawa：“水对氢敏感氧化钨薄膜的影响”传感器和执行器。

Kentaro Ito: "Positive temperature coefficient of resistance in metal-semiconductor contacts" J.Applied Physics. 65. 1982-1986 (1989)

Kentaro Ito：“金属-半导体接触中的正电阻温度系数”J.应用物理学。

K.Ito,T.Fukami: "PTC Effect in diode consisting of metal-insulator-semiconducting titanate ceramics structure" Ferroelectrics. 109. 161-166 (1990)

K.Ito，T.Fukami：“由金属-绝缘体-半导体钛酸盐陶瓷结构组成的二极管中的 PTC 效应”铁电体。