Chemical vapour deposition gases

In practical applications, gas-surface etching reactions are carried out in plasma reactors over the approximate pressure range 10 -1 Torr, and deposition reactions are carried out by molecular beam epitaxy (MBE) in ultrahigh vacuum (UHV below 10 Torr) or by chemical vapour deposition (CVD) in the approximate range 10 -10 Torr. These applied processes can be quite complex, and key individual reaction rate constants are needed as input for modelling and simulation studies—and ultimately for optimization—of the overall processes. 

The industrial application of Plasma Induced Chemical Vapour Deposition (PICVD) of amorphous and microcrystalline silicon films has led to extensive studies of gas phase and surface processes connected with the deposition process. We are investigating the time response of the concentration of species involved in the deposition process, namely SiH4, Si2H6, and H2 by relaxation mass spectroscopy and SiH2 by laser induced fluorescence. 

Applications involving ring transfer or loss. The kinetic lability, volatility, and Lewis acidity of heavy alkaline earth metallocenes have been the properties most important to their applications. The gas-phase decomposition of volatile metallocenes is useful in the preparation of thin films of alkaline earth-containing materials and in doping semiconductors. Reviews are available on the use of group 2 organometallic compounds as precursors for chemical-vapour deposition (CVD).2 3... 

As noted above, amorphous carbon films can be produced from carbon-containing gas phases (physical vapour deposition, PVD). They can also be produced from hydrocarbon-containing gases (chemical vapour deposition, CVD), Both PVD and CVD processes can be thermally-activated or can be plasma- and/or electric field-assisted processes (e.g., microwave assisted CVD and ion beam deposition). As a consequence a wide range of processes have been developed to form amorphous carbon films and a correspondingly complex nomenclature has evolved [70, 71],... 

Synthesis of intermetallics can be performed from their constituents involving the gas phase by using various methods. Notice that the presence of the gas phase may be relevant in several kinds of synthesis. A special role, however, is played by the gas phase in some groups of interrelated methods, which are generally defined as physical vapour deposition, chemical vapour deposition, vapour phase transport. 

Abstract A growing tendency in chemical vapour deposition is to produce ultra-thin films or nano-objects as particles, tubes or wires. Such an objective addresses the question of a better control of the main parameters which govern the nucieation and growth steps of the deposit. This chapter focuses on the interfacial phenomena that occur at both the solid surface and the gaseous phase levels. The role of surface defects, surface reactive groups, and autocatalytic phenomena on the nucieation step are discussed by means of representative examples from the literature. In an attempt to clarify gas-phase properties, the influence of the supersaturation parameter on the nucieation step is also described. 

Carbides and nitrides can be prepared in many ways (chemical vapour deposition, physical vapour deposition, precipitation of salts containing metal, carbon and oxygen followed by reduction and annealing, reaction of a metal or its oxides with a gas or with solid carbon). Carbides and nitrides are often nonstoichiometric with complex phase diagrams.4-9 The compounds sometimes contain multiple phases and impurities, notably oxygen. This can lead to even more complex compounds, like oxycarbides, carbonitrides or oxycarbonitrides. 

Deposition occurs by adsorption or reaction from a gas phase. This method may ensure excellent dispersion and very well controlled distribution of the active species. Chemical vapour deposition is an example of gas-phase deposition. 

Bruckner, J. and Mantyla, T. (1993), Diamond chemical vapour deposition using tantalum filaments in H2-CH4-O2 gas mixtures. Diam. Relat. Mater., 2(2 1 pt 1) 373-377. 

C. Pavelescu, C. Cobianu, L. Condriuc, and E. Segal, Etch rate behaviour of S1O2 films chemically vapour deposited from silane, oxygen and nitrogen gas mixtures at low temperatures. Thin Solid Films 114, 291, 1984. 

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