Chemically reactive plasmas, applications

Careful preparation of the deposition surface is an important step in the study of surface interactions with chemically reactive species from the gas plasma phase. Two types of silicon surfaces are of particular interest crystalline and amorphous surfaces that are exposed to the chemically reactive plasma species during the PECVD process. Crystalline surfaces, especially the Si(OOl) surface, are representative of commonly used crystalhne substrates (Si wafers) in various experimental studies and practical applications. Amorphous surfaces are representative growth surfaces at later stages of the PECVD process, after an a-Si H him has been deposited on the substrate. 

In a weakly ionized low-temperature plasma, various molecular species are abundantly generated either directly or indirectly as a consequence of electron collisions with molecules, and many of the molecular species readily react with other species. For this reason, one sometimes calls such a plasma chemically reactive. Applications of chemically reactive plasmas are widespread over organic and inorganic materials, in part because of the relatively low cost of generating of such plasmas. The large variety of chemically active species generated in a plasma is sometimes a disadvantage because they may initiate many reaction pathways, which may be difficult to analyze and to control. 

In addition to electrochemical polymerization, reactive monomers can be polymerized onto surfaces by using radio frequency (rf) plasma polymerization [194-197]. In this technique an electric discharge through the vapor forms a reactive plasma that chemically modifies the surface. Examples of applications of rf plasma-polymerized surfaces include the formation of (C2F4) films on fiber optic sensors for detection of volatile organics [198] and the formation of alkylamine surfaces on glass fibers by plasma treatment for subsequent chemical modification [199]. 

For the further optimization of the PDC system for VOC decomposition. It is necessary to know what happens on the catalyst sur ce under plasma application. Future R D efforts must be extended to the development of a new measurement technique of catalyst surface, identification of reactive chemical species on the surface of catalyst and time evolution of reaction products (intermediates) on the surface under plasma application. 

In this paper some applications of static SIMS to a variety of modified polymer surfaces are described. They include plasma treatments in reactive and inert gases, corona treatment in air, as well as thermal and ion beam modifications of polymer-metal interfaces. The examples presented and discussed here primarily serve to illustrate the capabilities of static SIMS for the study of such surfaces and interfaces. More detailed discussions of the actual chemical processes that proceed in several of the systems cited will be published elsewhere. 

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