Vapour phase deposition

Wang, 1., Ay, C-L, Lee, B-J., and Chen, M-H. (1989) Para-selectivity of dialkylbenzenes over modified HZSM-5 by vapour phase deposition of silica. Appl Catal, 54, 257-266. 

Many thin-film processing techniques have been developed and further improved in the search for the most suitable approach for a specific application. Typically thin films can be prepared from either the hquid or gaseous phase. Vapour-phase deposition processes, which are more popular, fall into the two main categories of physical and chemical vapour deposition. Atomic layer deposition holds a special position among the chemical vapour deposition techniques because it offers the possibility to produce thin films in a controlled, self-hmiting manner. 

In this example, the volatile precursor compounds were heated to obtain the product. Other energy sources are also used, notably electromagnetic radiation. An example of vapour phase deposition involving photo-decomposition is given in the next section on vapour phase epitaxy. 

Pretreatment primers. In this method of use the silane may be applied from a solvent solution, by vapour phase deposition or by plasma deposition although solvent application is the more usual. The solution usually contains water and silane at a concentration of 1-2 wt%. The applied film may be water washed before subsequent coating/bonding and/or heat cured. The solvent(s) used may be important in both the stability of the solution and the performance, particularly in the wet adhesion. It has been shown that the presence of water either in the solution or as a final rinse is important, particularly in the case of AAMS and presumably other silanes [1]. Other factors which are important include the concentration of silane the pH of the solution the thickness of the silane film deposited. 

There are two ways in which coatings can be applied thermomechanical processes (e.g. detonation gun, flame spraying and plasma spraying) and vapour phase deposition processes. The latter category can be subdivided into CVD (chemical vapour deposition) and PVD (physical vapour deposition). In the case of a CVD process, a chemical reaction takes place in an oven and as a result the coating material is formed and deposited on the object. Figures 11.7.9 and 11.7.10 are representations of two methods to apply coatings. 

The device may be formed by depositing alternating layers of cadmium telluride and mercury telluride by vapour phase deposition techniques and interdiffuse the layers, either during growth or subsequently, so as to form a mercury cadmium telluride layer. Reference is made to GB-A-2146663 (The Secretary of State for Defence, GB, 24.04.85) and GB-A-2203757 (Philips Electronic and Associated Industries Limited, GB, 26.10.88). 

Solids of elemental carbon in the sp bonding state can form a variety of graphitic structures. Graphite filaments can be produced, for instance, when amorphous carbon filaments formed by thermal decomposition of hydrocarbon species are subsequently graphitized by heat treatment. Graphite filaments can also grow directly from the vapour-phase deposition of carbon s ll which also produces soot and other novel structures such as the C i molecule. ... 

M. Niwa, H. Itoh, S. Kato, T. Hattori, and Y. Murakami, Modification of H-Mordenite by a Vapour-Phase Deposition Method. J. Chem. Soc., Chem. Commun., 1982, 819-820. 

Compared with other vapour-phase deposition methods, CVD method is perhaps the most complex. Unlike growth by physical deposition such as evaporation or Molecular Beam Epitaxy (MBE), this method requires numerous test runs to determine and reach suitable growth parameters, especially for single-crystal growth. The complexity of this method results from the following facts ... 

Abstract. Copper phthalocyanine (CuPc)-fullerene (C60) photovoltaic cells are produced by organic vapour phase deposition reaching efficiencies of 3%. The electronic transport properties of the devices are investigated as a function of the CuPc C60 absorber blend layer composition and its preparation temperature. The analysis of the transport properties of the devices employs the one-diode model. It is shown that the dominant recombination process takes place at the donor-acceptor interfaces of the CuPc and C60 absorber domains. The activation energy of recombination is related to the effective band gap of the blend layer. 

ITO/PEDOT PSS/CuPc C6o/Mg/Ag organic solar cells were fabricated on ITO (5 Q/squarc sheet resistance)-coated glass substrates. After solvent cleaning, the ITO/glass substrates were spin-coated by a PEDOT PSS layer and immediately transferred into the deposition chamber. A 70 nm-thick CuPc C60 blend layer was prepared by organic vapour phase deposition (OVPD ) [2, 3], The Mg/Ag back contacts were deposited by thermal evaporation in high vacuum (p 10 7 mbar) on non-air-exposed absorber surfaces. The device preparation details can be found elsewhere [4], The compositional and substrate temperature (Tsubstrate) investigations are carried out on type A and B devices with nonoptimised and optimised contacts, respectively. 

A new modification of indium sulphide, y-IngSg, has been prepared by a vapour-phase deposition method. A -Ray, topographical, and electron microscopy studies were carried out and the compound was found to decompose by the loss of sulphur in the electron microscope. The molecular constants of BSg have been determined from a study of the i.r. spectrum obtained at 4 K from the solid, trapped in neon matrices. 

High-qnality films of Cu, Ag or An can, for example, be obtained by vapour phase deposition from componnds (12.396) [6-8]. Laser CVD techniques from gold compounds such as (a) allows writing of gold on to GaAs substrates [9]. 

The solution of this problem was first given by Cabrera Burton [9] for the case of vapour phase deposition, the Lorenz [10] has adapted it to the electrochemical case. The solution has the form... 

Parylene coatings are unique in their method of application and were the first materials to be vapour phase depositable without the use of high surface temperatures, high vacuums or ultra-violet radiation. They are ideal for electronics coatings applications because, even though the dimer decomposition temperature is between 650 and 680 C, the piecepart to be coated can be maintained anywhere between room temperature and 150°C. 

As a conclusion of this section, let us characterise briefly the electronic structure investigations of one more group of materials whose properties are greatly dependent on surface effects. These are thin films made from refractory carbides and nitrides. These films find applications in microelectronics, optics and as coatings for cutting tools and other complicated multilayered materials. Such films can be produced by different methods, such as thermal deposition or laser evaporation, (Morchan, 1982), molecular-beam epitaxy and cathode sputtering (Herman, 1982 Cho, 1983), plasma condensation in vacuum with ionic bombardment of the substrate surface (Dorodnov and Potrosov, 1981), chemical vapour-phase deposition (Anikeev, 1977 Anikin, Anikeev and Zolotaryova, 1979), etc. 

For the first time, in 1990, Allford and Place reported about the feasibiHty of producing pyrolants from vapour phase-deposited materials. In addition to thermite-type systems such as Ti/Pb304, they also reported about the preparation of composite metal/fluorocarbon films produced by vapour phase deposition of Mg on polyte-trafluoroethylene (PTFE) tape [1, 2], The product obtained this way is a silvery tough but flexible tape. A schematic setup of the apparatus is given in Figure 16.1. 

Powell, G., Place, M., Leach, C., James, R. and Hall, J. (1997) Developments in vapour phase deposited pyrotechnic materials. 28th International Annual ICT Conference, Karlsruhe, Germany, June 24-27, p. 63. 

SP Khedkar, S Radhakrishnan. Long-term aging and stability of conductivity in vapour phase deposited polypyrrole films. Polym Degrad StabU 1997 57 51-58. XB Chen, J Devaux, J-P Issi, D Billaud. The conducting behavior and stability of conducting polymer composites. Polym Eng Sci 1995 35 637-641. 

Polymer films produced by a glow discharge often possess chemical and physical properties that are superior to conventionally polymerized materials [110,111]. They are prepared by a totally dry vapour phase deposition process and may be conformally coated onto virtually any substrate, thereby completely changing the surface properties of the substrate. Further, the substrate may be cleaned by the plasma prior to deposition and, under the correct conditions, it is often possible to graft the deposited polymeric film to the underlying substrate. 

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