Thin film technology limitations

WESTERN AREA POWER ADMINISTRATION Interstate Power and Light Company FPL GROUP INC Investec Limited IDATECH LLC Iowa Thin Film Technologies POWERFILM INC IP 1 MESA ENERGY INC... 

The limits of independently addressable microbiosensors in an array have been explored on the basis of microdisc electrode arrays fabricated by thin-film technology. Cross-talk between the discrete enzyme-containing sensor elements was observed and the proximity limit was found to be about 100 (xm [261]. 

So far, we have considered catalytic materials that conform to the side walls of a microreactor. A downside to a functionalized coating at a channel wall is the limited catalytic surface area that can be provided. As an alternative, thin-film technology can be used for depositing catalytic materials on more complex three-dimensional surfaces inside microchannels [49]. Impregnation methods can also be used on porous silicon surfaces [50]. The mass transfer rates described for such structures are sufficient for all but the fastest heterogeneous reactions. 

It should be noted that the second and the third approaches assume a subsequent high-temperature treatment which will reduce the effectiveness of the methods and limit their application. It is obvious that the third approach cannot be used with thin-film technology this approach is limited mainly to ceramics, for which high-temperature annealing is one of the usual steps in the manufacture of chemical sensors. The second and third approaches also assume that at least one of the components participating in solid-phase reactions has sufficient mobility at the annealing temperatures used. Regarding the first approach, for its realization, one could use all methods of synthesis and deposition, as described in Korotcenkov and Cho (2010). However, the most effective for this approach are sol-gel synthesis processes and aerosol-phase deposition methods. 

For characterization purposes of bulk or thin-film semiconductors the features at Eq and E] are the most useflil. In a number of technologically important semiconductors (e.g., Hgi j d Te, and In Gai j ) the value of. ) is so small that it is not in a convenient spectral range for Modulation Spectroscopy, due to the limitations of light sources and detectors. In such cases the peak at E can be used. The features at Eq and are not useflil since they occur too far into the near-ultraviolet and are too broad. 

GaN as a semi-conducting material for electronics is about to be launched on the market, especially for the use in blue- and UV-emitting LEDs and laser diodes [2]. The material is deposited on crystalline substrates like sapphire using thin-film epitactical techniques. Often, metal-organic chemical vapor deposition (MOCVD) is used. The necessity for such technologies limits the production rate and pushes up costs. 

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