Plasma deposition technique

FIGURE 2.2 Schematic of Liquid Injected Plasma Deposition technique. 

The ordered P AA back-side and structured Al surface were used to produce self-organized metal nanoparticles. We used Au or amorphous carbon as add-layer for deposition of Ti or Fe nanostmctures. Both these metals have a weak wetting of the add-layer. The deposition was performed by a laser induced plasma deposition technique. In this process the energy of ions was about 20 eV. The highly ordered curved substrate surface defined position of the deposited clusters providing formation of highly ordered arrays of metal nanoclusters. A perspective application of such structures for terabit memory was demonstrated. For example, Ti nanoclusters covered by native oxide demonstrated irreversible transformation of I-V characteristics from barrier-like to the ohmic behavior after the action of current supplied by a tip of conductive AFM. 

Polymeric resists are usually deposited on the substrates by spin coating, followed by baking in order to eliminate the residual solvent and to suppress mechanical stress. Some attempts have been made to deposit polymeric films by the plasma deposition technique [5]. 

For food packaging applications a thin silicon oxide film on PP may be required to ensure O2 and H2O barrier properties [160]. Such thin films can be grown using plasma deposition techniques. A pretreatment of PP is necessary to improve adhesion. Both treatments in Ar and Ar-N2 mixture plasmas enhance the adhesion of the silica layers to PP. This is attributed to crosslinking (detected by in situ UV-visible ellipso-metry measurements) and to nitrogen functionalities, which result in acid-base interactions between PP... 

Operating at ambient pressure allows industry to move from batch to continuous processing and also facilitates much simpler equipment designs with reduced maintenance requirements due to the lack of vacuum pumps, seals, etc. Besides activation and functionalization of surfaces, the APP technology also involves different coating processes. Recent advances in this technology have included the development of aerosol-assisted plasma deposition techniques. A schematic view of an aerosol-assisted DBD treatment of foils is shown in Fig. 20.30. 

Finally, one more type of water splitting cells should be mentioned, namely integrated photovoltaic-electrolysis (PV-PEC) cells. In this type of devices, the photovoltaic cell and the electrolyser are combined into a single system, in which the light-harvesting solar cell is one of the electrodes. Very often, thin-film solar cells fabricated by the cold plasma deposition method are employed in the PV-PEC devices (Kelly Gibson, 2006). A diagram of such a system with a simply a-Si H solar cell is shown in Fig. 8. There is no doubt that the role played by the cold plasma deposition technique in the creation of such systems is unquestionable (see Sec. 4.1.). 

The possibility of plasma copolymerization and the production of composite materials allows to design at the molecular level thin films of very low electronic conductivity, but with very high ionic conductivity. Such films can be obtained in the polymer-like form (polymer electrolytes) and as ionic glasses (solid oxide electrolytes). These new solid electrolyte systems enable us to replace the conventional solid electrolytes by the much thinner elements, which in addition have all the other advantages of plasma fabricated materials, for example, selective permeability. Thin films of solid electrolytes produced by cold plasma deposition techniques have been of particular interest recently. 

Another issue, which is only briefly mentioned in this Chapter, is the use of cold plasma for surface modification of conventional materials. We can thus improve the properties of "conventional" elements relevant to the construction of electrochemical cells electrode substrates, electrodes themselves, separators, etc. Research interest in this field of the cold plasma technology is comparable to that which is focused on entirely new materials produced by plasma deposition techniques. The use of the plasma treatment technique in... 

Various plasma diagnostic techniques have been used to study the SiH discharges and results have helped in the understanding of the growth kinetics. These processes can be categorized as r-f discharge electron kinetics, plasma chemistry including transport, and surface deposition kinetics. 

Many materials have been deposited by PECVD. Typically, the use of a plasma allows equivalent-quaUty films to be deposited at temperatures several hundred degrees centigrade lower than those needed for thermal CVD techniques. Often, the plasma-enhanced techniques give amorphous films and films containing incompletely decomposed precursor species such as amorphous siUcon (i -Si H) and amorphous boron (i -B H). 

Plasma CVD Plasma chemical vapor deposition. Technique for synthesizing materials in which chemical components in vapor phase excited by plasma react to form a solid film at some surface. 

Plasma analysis is essential in order to compare plasma parameters with simulated or calculated parameters. From the optical emission of the plasma one may infer pathways of chemical reactions in the plasma. Electrical measurements with electrostatic probes are able to verify the electrical properties of the plasma. Further, mass spectrometry on neutrals, radicals, and ions, either present in or coming out of the plasma, will elucidate even more of the chemistry involved, and will shed at least some light on the relation between plasma and material properties. Together with ellipsometry experiments, all these plasma analysis techniques provide a basis for the model of deposition. 

In order to relate material properties with plasma properties, several plasma diagnostic techniques are used. The main techniques for the characterization of silane-hydrogen deposition plasmas are optical spectroscopy, electrostatic probes, mass spectrometry, and ellipsometry [117, 286]. Optical emission spectroscopy (OES) is a noninvasive technique and has been developed for identification of Si, SiH, Si+, and species in the plasma. Active spectroscopy, such as laser induced fluorescence (LIF), also allows for the detection of radicals in the plasma. Mass spectrometry enables the study of ion and radical chemistry in the discharge, either ex situ or in situ. The Langmuir probe technique is simple and very suitable for measuring plasma characteristics in nonreactive plasmas. In case of silane plasma it can be used, but it is difficult. Ellipsometry is used to follow the deposition process in situ. 

In fact, an apparent doping effect was also reported by Schwan et al. [39] in a-C(N) H films deposited by the highly ionized plasma beam deposition technique in C2H2-N2 atmospheres. Schwan et al. also observed thermally activated behavior for the conductivity. As reported by Silva et al. [14], they also observed increasing optical gap, and decreasing ESR spin signal, but the Urbach energy was found to increase. 

The talk will briefly review some of these developments ranging from high temperature equilibrium plasmas to cool plasmas, PECVD, ion implantation, ion beam mixing and ion assisted etching and deposition. Brief consideration will also be given to sputtering and ionised cluster beam deposition techniques in inorganic synthesis. 

In the case of H in low-temperature deposited silicon nitride films, ion beam techniques have again been used to calibrate IR absorption. The IR absorption cross sections most often quoted in the literature for Si—H and N—H bonds in plasma-deposited material are those of Lanford and Rand (1978) who used 15N nuclear reaction to calibrate their IR spectrometry. Later measurements in CVD nitride films, using similar techniques, confirmed these cross sections (Peercy et al., 1979). 

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