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.

我们研究了金属-半导体氧化物触点，以开发高选择性和灵敏度的氢探测器和正温度系数（PTC）热敏电阻。本研究的目的是阐明这些传感器的基本机制，并优化器件制造的工艺参数。我们发现，由Pd薄膜和半导体Sr_xBa_<1-x>TiO_3陶瓷组成的二极管在氢气作用下正向电流增大。势垒高度依赖于氢的浓度，其方式与Pd - MOS结构相同。Au/阳极氧化/钛酸锶钡陶瓷结构的反向电流表现出PTC效应和电压依赖关系，符合Fowler-Nordheim方程。采用溅射非晶氧化钨薄膜沉积在玻璃基板上，再覆盖半透明Pd薄膜，制备了透射型氢传感器。氢对光谱透过率的降低在900 nm处有一个峰值。传感器的响应时间为10^2 s数量级。虽然在200°C的真空中退火后，传感器的氢灵敏度大大降低，但随后暴露在100°C的水蒸气中并在室内空气中老化后，传感器部分恢复了初始响应时间。反射型氢传感器由在W片上形成的阳极氧化膜，然后覆盖半透明的Pd或Pt膜组成。其响应时间约为10秒。x射线衍射结果表明，该薄膜由WO^3·H^2O组成。该传感器的显色机制被认为是基于氢钨青铜的形成和随之增加的薄膜电子浓度。着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W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。