High vapor pressure precursors

The best results were obtained with compound 21 that exhibited high vapor pressure and low decomposition temperature (<523 K). Various CVD conditions were applied and gave in all cases shiny, dark-brown deposits.43 XRD and XPS analyses of the deposits indicated the presence of a vanadium carbonitride phase with little contamination from oxygen and free carbon. The films were less adherent on steel substrates than on silicon ones. The steel substrates seemed to suffer corrosion due to the presence of Cl-containing species. We had noticed the same feature in the case of Cl-containing precursors to vanadium carbide. Therefore, in order to increase the volatility of compound 23 and to reduce the Cl content of the molecule, we prepared compounds 24 and 25. Unfortunately, the yields obtained in their syntheses were much too low to permit TG and CVD experiments. 

The metalorganic precursor compounds that have been most commonly used to grow thin films of semiconductors and related materials are listed below in Table I, along with the currently available vapor pressure data. These precursors are typically pyrophoric liquids or high-vapor-pressure solids. The simple metal alkyls (methyl and ethyl derivatives) are the most often employed for the growth of III-V compound semiconductors since they have reasonably high vapor pressures and can be readily delivered using a H2 carrier gas and precursor source temperatures conveniently near room temperature. 

Uses Inexpensive Precursors Soluble precursors are used instead of expensive, high vapor pressure organometallics. 

Mixed metal Fe-Co alloys of variable composition have been prepared by the sonication of controlled stoichiometries of Fe(CO)s and Co(CO)3(NO). These compounds were chosen as precursors because of their solubility and high vapor pressure. Similar results have been obtained in a mixed-phase reaction by the sonication of Fe(CO)s and Co2(CO)8, both in decane and using Fe(CO)s as the sonication medium.The resulting mixed metal alloys were... 

Deposition of nanoparticles from vapor phase, as opposed to wet impregnation methods, does not alter the porous matrix and ensures that the guest phase will be distributed throughout the matrix, thanks to its open porous texture. The general applicability of this approach is limited by the availability of precursors with a sufficiently high vapor pressure to give rise to volatile by-products. 

It requires chemical precursors (the starter materials) with high vapor pressure which are often hazardous and toxic. 

Uses liquid or gaseous precursors wiiri high vapor pressure Uses precursors with low vapor pressure. 

The preparation of the precursor solution begins with the dissolution of silicon alkoxide or its derivatives in an organic solvent like hexane that meets the conditions (1) immiscible with water, (2) lower density than water, and (3) relatively high vapor pressure. Among commercially available silicon alkoxides and their derivatives, ethyl silicate 40 (E-40), partially hydrolyzed tetraelhoxysilane (TEOS) comprising the 5-membered oUgomers, turned... 

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