Chemical vapour deposition sensor

Figure 1.8a showed a scheme of the CNTs NO2 sensor layout for NO2 detection with limits as low as 10 ppb [108], It was prepared by a radio frequency plasma enhanced chemical vapour deposition (r.f. PECVD) on Si/Si3N4 substrates. The thin film (5 nm) of Ni catalyst was deposited onto Si3N4/Si substrates provided with platinum interdigital electrodes and a back-deposited thin-film platinum heater... 

Logothetis, E. M. and Kaiser, W. J. (1983), Ti02 film oxygen sensors made by chemical vapour deposition from organometallics. Sensors and Actuators, 4,333-40. 

Binions, R. (2007) A comparison of the gas sensing prop>erties of solid state metal oxide semiconductor gas sensors produced by atmospheric pressure chemical vapour deposition and screen printing. Measurement Science and Technology 18. 

Shaw, G, Parkin, I. P, Pratt, K. F. E. and Williams, D. E. (2005) Control of semiconducting oxide gas-sensor microstructure by apphcation of an electric field during aerosol-assisted chemical vapour deposition. Journal of Materials Chemistry 15, 149-54. 

CNTs find applications in the areas such as micro electronics, field emission displays. X-ray sources and gas sensors. Single waUed and multi-waUed CNTs can be grown using high pressure arcs, laser ablation and chemical vapour deposition. 

In order to improve performance, inorganic oxides other than Si02 for pH sensors such as AI2O3, Si3N4 and Ta20s have been deposited on top of the Si02 by chemical vapour deposition, in order to increase sensitivity and decrease the hysteresis and drift of Si02-based ISFETs. 

In electrical engineering, they have utilisation potential in feeler sensors, resisters, magnetic shields, lossless optical fibres and superconductors. Methods of manufacture vary, but include the chemical and physical vapour deposition methods, the electrolytic deposition method, the atomised metal spray method, and a method in which powdered material is first melted in a plasma jet and then deposited... 

From an examination of literature reports one can classify sensor applications into several categories. The earliest applications of piezoelectric sensors were as simple mass detectors where material was deposited to the device surface in a non-selective manner. In later work, mass sensors were transformed into chemical sensors by developing surface coatings which selectively bound gases from a vapour-phase chemical system. This increase in sophistication represented a major advance in the analytical capabilities of piezoelectric sensors. The manner and selectivity with which surface binding is controlled is the critical element in producing a practical chemical sensor and... 

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