Reactive deposition

Semiconducting CrSi2 nanocrystallites (NCs) were grown by reactive deposition epitaxy (RDE) of 0.6 nm Cr at 500, 550 and 600 C. The NCs were covered by epitaxial silicon at 700 °C with different thickness. It was observed that CrSi2 is localized nearthe surface in the form of 20 nm 2D nanoislands and 40-80 nm 3D NCs. The 2D nanoisland concentration is found to be reduced by the Si cap growth, while the large 3D NCs appear at the depth of Cr deposition and they also appear at the surface. 

It was shown that chromium disilicide (CrSi2, Eg= 0.35 eV) nanociystallites are embedded in monocrystalline lattice by reactive deposition epitaxy (RDE of Cr) and Si molecular beam epitaxy (MBE) [1]. Redistribution of CrSi2 NCs has been observed in silicon-silicide-silicon heterostructures with one embedded layer by HR XTEM data [2]. 

Glass films are used in the semiconductor industry because of their dielectric properties, and are used for encapsulating integrated circuits and other electronic devices because they provide a hermetic seal. Glass films are formed by both reactive and non reactive deposition methods, (e.g., evaporation, sputtering, and ion implantation or ion platting for the latter). 

Pure and NaP-modified MnOx-catalysts were used in our study. Due to easy visualization by AFM, the MnOx layer was placed on a Si-wafer substrate (1 cm x 1 cm plate), by a reactive deposition technique. The sample preparation was carried out in a vacuum installation equipped with an resistance evaporator. Metallic manganese (99.8%) as a source and a Si wafer with a surface orientation (111) and resistivity of 7.5 ohm/cm as support, were used. During MnOx deposition, an oxygen partial pressure of ca 10 torr, in dynamic mode, was maintained. Before used for the catalytic purpose, MnOx samples were calcined in air at 700°C for 60min. In order to prepare the NaP-modified catalyst, the MnOx samples were impregnated in a diluted Na4P20 solution (5 wt %), dried and finally calcined at 500° C, in air during 30 min. The interaction with methane was performed in a quartz reactor in a methane atmosphere at 700° 5° C. 

In physical vapour deposition, PVD, coatings are produced on solid surfaces by condensation of elements and compounds from the vapour phase. The principles are based generally on purely physical effects, but PVD may also be associated occasionally by chemical reactions. Some of these chemical reactions are used intentionally in a special physicochemical film deposition technology, reactive deposition. Reduced to its essence, physical vapour deposition involves three steps ... 

This results in random enveloping deposition with particles of relatively high energy. The throwing power is a typical effect in ion plating. The chemical reaction with activated gas atoms, or with gas ions, is an important process for the reactive deposition. It is well known that many compounds are not volatile in stoichiometric molecules so that reactive deposition in the presence of reactive gases is an impor-... 

Reactive deposition has developed into a powerful technology over the last 30 years. It is historically interesting to note that in early studies, Soddy [388] found in 1907 that calcium vapour is highly reactive to most gases and that Langmuir [389] in 1913 investigated the formation of tungsten nitride by vapour-phase reaction of the elements. 

With all reactive depositions, it is a prior condition to have an adequate supply of reactants which can undergo collisions and react following the chemical reaction to form the desired compound film. There have been numerous theoretical treatments and reviews of reactive evaporation [390-397] of reactive sputtering [398-415] and to a smaller extent of reactive ion plating [416-422]. 

The difference between Cf and C f is easy to calculate. For a mass corresponding to a 2% shift in starting frequency, the difference in areal density using C f instead of C, is about 4%. For accurate mass determinations, this variable sensitivity has to be considered. The quartz crystal monitor can also record the rate of deposition, as already mentioned above. Rate measurements are very important especially in reactive deposition. The rate is obtained by electronic differentiation of the mass-dependent frequency change with respect to time. The slightly varying mass sensitivity with increasing mass load need not be considered for rate measurements. 

Fernandes NE, Fisher SM, Poshusta JC, Vlachos DG, Tsapatsis M, Watkins JJ. Reactive deposition of metal thik(TE Please clarify if it is Thik or Thick ) films within porous supports from supercritical fluids. Chem Mater 2001 13 2023. 

Enhancement of absorption bands in the IR spectra of ultrathin films in the presence of discontinnons (islandlike) nnder- and ovemanolayers of Ag and An was discovered by Hartstein et al. [356] in the early 1980s. Although these researchers believed that they observed an increase in the vCH band intensities for p-nitro-benzoic acid (p-NBA), benzoic acid, and 4-pyridine-COOH films, it was recently shown [350] that the spectra reported are in actual fact due to fully saturated hydrocarbons (possibly vacuum pump oil). In any case, this discovery has stimulated various research activities and led to the development of surface-enhanced IR absorption (SEIRA) spectroscopy. To date, the SEIRA phenomenon has been exploited in chemical [357] and biochemical IR sensors (see [357-360] and literature therein), in studying electrode-electrolyte interfaces [171, 361-365], and in LB films and SAMs [364, 366-370]. Other metals that demonstrate this effect are In [371] and Cu, Pd, Sn, and Pt [372-375]. The metal films can be prepared by conventional metal deposition procedures such as condensation of small amounts of metal vapor on the substrate, spin coating of a colloidal solution, electrochemical [388], or reactive deposition [299] (see also Section 4.10.2). 

Guzman, L., Celva, R., Miotello, A., Voltolini, E., Ferrari, R, Adami, M. (1998) Polymer surface modification by ion implantation and reactive deposition of transparent films. Surf Coat. Tech., 103-104,375-379. 

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