Hydrogen, detection

Hydrogen detection in this type of meter is achieved using an ion pump, mass spectrometry or thermal conductivity detectors. ... 

Technology Approaches to Palladium-Based Hydrogen Detection and Sensing... 

The interference to the hydrogen detection of C-I-S structures caused by varying amounts of water vapor is also summarized in Table II. As seen in that table, high concentrations of H2O vapor lower the sensitivity of Pd/SiOx/Si diodes whereas water vapor, in general, lowers the sensitivity of Pd/TiOx/Si diodes at room temperature. 

The effect of elevated operating temperatures on the interference to hydrogen detection arising from O2 for Pd/SiOx/Si diodes is also seen in Table III as a function of H2 ppm levels. As may be noted from this table, the reduced sensitivity to hydrogen, especially at low concentrations, caused by the interference from oxygen is not significant at elevated device operating temperatures i.e., temperature effects dominate. 

The influence of elevated operating temperatures on the interference to hydrogen detection arising from water vapor is generally advantageous. That is, water vapor does not have a detrimental effect on SiOx-based C-I-S devices for T > 100°C. This is apparently due to water leaving the sensor surface for T > 100°C. We also note that, as at room temperature, CO does not interfere with hydrogen detection in diode sensors at elevated temperatures (14). 

The effect of several ambients on the speed of hydrogen detection is seen for room temperature in Figure 13. The hydrogen level is 600 ppm and the ambients are dry air, dry 100% O2 and dry 100% Ar. As may be noted, device response to hydrogen is the fastest in the O2 ambient and the longest in the Ar ambient. Figure 14 shows the effect of CO in device response to hydrogen. As may be seen, CO slows down the room temperature response. 

Interferences. Figures 13, 16, 17, and 18 together with Table II provide information on O2, CO, or H2O interferences to hydrogen detection observed when using Pd/Si02/Si capacitor devices. As may... 

The effect of the presence of water vapor on hydrogen detection at room temperature for C-I-S capacitor sensors is seen in Figure 16. The data show that water vapor tends to reduce the sensitivity to... 

D. Filippini and I. Lundstrom, Hydrogen detection on bare Si02 between metal gates, J. Appl. Phys., 91(6) (2002) 3896-3903. 

The thin film fiber optic reflective sensor based on palladium catalyzed W03 appears to work well for detecting hydrogen, but its response time is too slow for critical applications. The sensitivity and speed of hydrogen detection can be enhanced by using the sensor film in a SPR configuration. However, in such a configuration the rapid desorption of water vapor can lead to a false indication of hydrogen whenever the sensor is exposed to a dry... 

This work is divided into four main sections. First, in Part II, we discuss the influence of adsorbate effects on the conductivity of a-Si H material. In Part III the possibility of using a-Si H for thermistor applications is considered and justified. Part IV covers in some detail the studies of a-Si H-based MIS structures for hydrogen detection, while Parr. V deals with ACS devices based on a-Si H FETs. We will consider the specific example of a Pd MOSFET H2 sensor. 

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