Metal-oxide-semiconductor hydrogen

A wide variety of solid-state sensors based on hydrogen-specific palladium, metal oxide semiconductor (MOS), CB, electrochemical, and surface acoustic wave (SAW) technology are used in the industry for several years. Microelectromechanical systems (MEMS), and nanotechnology-based devices for the measurement of hydrogen are the recent developments. These developments are mainly driven by the demands of the fuel cell industry. Solid-state approaches are gaining rapid popularity within the industry due to their low cost, low maintenance, replacements, and flexibility of multiple installations with minimal labor. 

Fogelberg, J. and Petersson, L.-G., Kinetic modeling of the H sub 2-0 sub 2 reaction on palladium and of its influence on the hydrogen response of a hydrogen sensitive palladium metal-oxide-semiconductor device, Surface Science, 350(1-3), 91,1996. 

Field-effect transistors (FETs) Heterojunction bipolar transistors (HBTs) High electron mobility transistors (HEMTs) Metal oxide semiconductor FETs (MOSFETs) Single-electron transistors (SETs) Single-heterojunction HBTs (SH-HBTs) Thin-film transistors (TFTs) hydrogenated amorphous silicon in, 22 135... 

Variation of the nature of the gate electrode results in the different types of FET. For example, in the metal oxide semiconductor FET (MOS-FET) palladium/palladium oxide is used as the gate electrode. This catalyti-cally decomposes gases such as hydrogen sulphide or ammonia with the production of hydrogen ions, which pass into the semiconductor layer. An enzyme may be coated on the palladium, e.g. urease, which catalyses the production of ammonia from urea and thus provides a device for the measurement of this substrate. 

Kim, Y. I. Atherton, S. J. Brigham, E. S. Mallouk, T. E. Sensitized layered metal oxide semiconductor particles for photochemical hydrogen evolution from non-sacrificial electron donors, J. Phys. Chem. 1993, 97, 11802. 

In related studies, Hoffmann and co-workers [142,143,150-153] examined the rates of photooxidation of selected organic compounds and the production of hydrogen peroxide on a variety of metal oxide semiconductors. In general, electron transfer occurs from the conduction band to dioxygen adsorbed on the surface of the excited state metal oxide as follows ... 

The production of molecular hydrogen was measured in the effluent gas of seven fermentations [58]. The aim of this primary investigation was to study the use of a H2-sensitive metal-oxide-semiconductor structure in physiological studies of Escherichia coli. In order to yield more information, the metabolic heat was measured with a flow micro calorimeter in parallel with the determination of molecular hydrogen. 

Tuttle, B.R., McMahon, W. and Hess, K. (2000) Hydrogen and Hot Electron Defect Creation at the Si(100)/SiO2 Interface of Metal-Oxide-Semiconductor Field Effect Transistors. Superlatt. Microstruct., 27, 229-233. 

Gas sensitive palladium metal oxide semiconductor structures (MOS) have been developed for the measurement of hydrogen and ammonia (Lundstrom, 1978). For indication of NH3 the gate has been covered additionally with iridium (Fig. 12). 

Kang, B. S., Ren, E, Gila, B. R, Abernathy, C. R. and Pearton, S. J. (2004b) AlGaN/ GaN-based metal-oxide-semiconductor diode-based hydrogen gas sensor . Applied Physics Letters, 84(7), 1123-1125. 

PVD has been used to fabricate metal oxide semiconductor gas sensors widely - for example, Michel et al (1995) used magnetron sputtering to produce Sn02 films. The films were shown to have a level of conductivity and, upon exposure to hydrogen, the conductivity was shown to increase. Gupta... 

Keywords Anodization Catalysts Metal oxide semiconductors Photoelectrochemical hydrogen production... 

Metal oxide semiconductor electrodes also differ from bare metal electrodes with respect to interactions with water. Interfacial region in which water properties differ significantly from those found in the bulk phase is generally more extensive than for metal electrodes. Significant interfacial water structure can extend to several molecular layers from oxide surfaces. Also, the inner monolayer of water can be rotationally immobile due to hydrogen bonding, a feature that is absent at pure metal surfaces. 

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