Metal-Semiconductor Contacts for Sensor Application

我们有一个研究金属半导体氧化物接触器来开发一个高度选择性和敏感的氢检测器和一个正温度协同剂（PTC）热敏剂。我们在此研究中的目标是为这些传感器和设备优化过程参数的elucidate fundamental Mechanisms for these sensors and optimize process parameters of the device fabrications.我们找到了用于Pd thin film and semiconducting Sr_xBa_<1-x>TiO_3 ceramics increases on exposure to hydrogen的正向电流。屏障高度取决于氢浓度在相同的方式，即Pd MOS结构。Au/anodic oxide/ barium strontium titanate？amics 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。在光谱传输中，氢在900纳米的波长处有一个峰值。传感器的响应时间是10^2 s的顺序。Though the hydrogen sensitivity considerably degraded after annealing at 200 ℃ C in Vacuum， the sensor partially recovers the initial response time after subsequent exposure to water vapor at 100 ℃ 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 semittransparent Pd or Pt film。它的响应时间是10秒的命令。It is revealed by X-ray diffraction that the film consists of WO^3·H^2 O。传感器的染色机制被认为是基于氢钨青铜的形成和一个在电子集中的结果增加。确定颜色反应的速率步骤很可能会导致水辅助质子扩散。W表的最佳抛光和修饰方法也已提出。

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.