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One of the main specific features of the cold spray process is localisation during particle impact deformation. The resultant adiabatic shear instability is the phenomenon that is known to play a major role in the particle/substrate and particle/particle bonding and coating structure formation during the cold spray process. In this article, the cold spray process is numerically simulated as an impact between a single spherical particle with the substrate, and comparison with experimental results for Armco iron and stainless steel particles is made. To describe a deformation behavior of the two materials at high strain rates, the Johnson–Cook model has been chosen. The results indicate that the model accurately captures the grain distortion in the impact zone for both materials. This approach provides valuable information on the characterisation of the strain localisation at the particle/substrate interface.

The potential of pulsed laser deposition in an applied uniform electrostatic field was investigated. A flat, positively charged, fine-celled-grid counter electrode was used to provide bias voltage of up to +50 kV with respect to the substrate. This enabled control of the atomic mixing and made it possible to initiate chemical bond formation at the interfaces of the films formed by deposition from the laser-induced plume. As an example, the results of multilayer 56Fe/MoSx/57Fe film deposition are presented. At first, a bilayer MoSx/57Fe film was grown in the absence of the electric field. This was followed by 56Fe film deposition in an applied field. A relatively sharp interface between the MoSx and 57Fe films was observed. In contrast, after 56Fe deposition, effective atom mixing was observed and new chemical bonds between Fe, S and Mo were detected. By penetrating through the interface, accelerated 56Fe ions gave rise to the growth of an amorphous layer of up to 50 nm in thickness. It consisted of rather evenly distributed Fe, S and Mo atoms (at total ion dose of 2.5×1016 cm−2). The ion flux destroyed MoS chemical bonds, and the S atoms released preferably bound Fe atoms, thus forming a FeS2-type phase. The Mo atoms, as a lower-oxidation-state species (apparently together with S atoms), were localized in the vicinity of Fe atoms and affected the hyperfine magnetic fields. The technique developed has made it possible to study the ion-induced processes occurring at the interfaces of multilayer films. It can also be applied to improve the tribological functionality of thin films.

The results of comparative measurements of annihilation rate coefficients of fluorine radicals (Ka) are presented. These results are obtained by means of three modifications of time-resolved actinometry: 1. by conventional techniques with square pulse delay time variation in a full discharge power modulation mode; 2. with partial discharge power modulation by square pulses; and 3. with full discharge modulation by a series of short pulses in the afterglow stage. Intensity microchronograms of spectral lines of F radicals (703.7 nm), Ar (750.4 nm) and their background values (701.7 and 748.4 nm) were obtained by means of a dedicated time-resolved (2.5 μs) acousto-optic spectrometer. The spectral resolution was equal to 0.35 nm. Fluorine radicals' kinetic annihilation curves were deduced by processing the measured chronograms according to the basic actinometry equation. Ka values were determined from exponential decay fits of the dropping parts of the kinetic curves. In addition, in the first of the above-mentioned modifications, a residual concentration level was used in an integral expression for the reactive particle concentration at the annihilation stage. The importance of this parameter was shown in earlier papers.

A method of emission actinometric measurement of kinetic parameters of plasmachemical reactions is proposed including the determination of the kinetic order, annihilation rate constants of chemically active particles and their characteristic lifetimes. The basis of the method is the time-resolved actinometry and the discharge power modulation by a probing pulse series at the afterglow stage with a time resolution of Δ t ≥1 μs. Kinetic accumulation and annihilation curves at this stage are derived from the microdynamics of spectral line intensitities of the selected actinometric pairs. The measurements of spectral line peaks and their background values controlled by the PC microcomputer are carried out at four to nine wavelengths in a quasi parallel mode of an acoustooptic spectrometer. The duration of a measurement cycle of 100 repeated measurements at four wavelengths with a time resolution of 25 μs took no more than 50 s. The values of kinetic parameters can be derived from the analysis of the logarithmic plot of the kinetic curve of particle annihilation. Measurements of the heterogeneous annihilation rate constant for atomic fluorine have been carried out in the SF6 RF plasma with an addition of argon as an actinometer in a standard diode-type Al-reactor. The values of pulse length and duty cycle of probing pulses are determined experimentally for measuring the kinetic parameter of fluorine annihilation in such a way that there is no substantial increase of the fluorine residual concentration level. Based on the analysis of the experimental kinetic curve of heterogeneous annihilation, a solution taking into account a procedural error of the proposed method due to nonzero level of the residual concentration of the observed particles at the afterglow stage is proposed. The experimentally obtained value of the fluorine heterogeneous annihilation rate constant measurement error is about (15±2)% at a residual concentration level of about 10%. The measurement reproducibility of fluorine heterogeneous annihilation rate constant is 3–5% in the unloaded and silicon wafer loaded reaction chamber with actinometer concentrations of 2.5 and 5.6%.

Spectral investigations were carried out in a plasma-enhanced chemical vapour deposition (PECVD) process using hexamethyldisiloxane (HMDSO) thin film deposition. The experiments were performed in a closed reactor with r.f. plasma generation in the pressure range of 20–40 Pa and power range of 10–20 W. It is shown that the emission lines of atomic hydrogen (486 nm) and CH radicals (431 nm) are the most informative lines from the point of view of the process dynamic control, because hydrogen is the final product of the discharge and CH is an indicator for the last intermediate products (CxHy) of the process obtained. Other species (Si and O) are built in the deposited coating. The excitation energy of the hydrogen lines (≈ 12 eV) permit the use of the argon emission line at 750 nm as an actinometer (≈ 11 eV ). A problem for using actinometry is the large difference of the exciting level of the CH band (≈ 3 eV). That is why in the following article is shown as only a first approximation for characterising this PECVD process. By adding argon (up to 10%) the process dynamic was controlled in the hydrogen and CH radicals concentration measurement mode. The measurement was realised by using spectral signals measured at 5–8 (peak and its background) different wavelengths in the quasi parallel mode of an acoustooptical spectrometer. The measured curves of the relative H and CH concentrations demonstrate the CH accumulation due to plasma chemical conversion of HMDSO during the first two stages of the process duration. The final stage of the process is characterised by the dissociation of CH radicals, which results in a synchronous increase of the hydrogen signal and decrease of the CH radicals signal causing the existence of free carbon, which appears as carbon enriched coverage on reactor walls.

The solution is proposed to the problem of the relative concentration dynamics control of chemically active particles in the low temperature gas plasma as well as the investigation of their generation and annihilation by means of time-resolved actinometry. A special small-size acousto-optic spectrometer has been constructed capable of spectral resolution of 0.1–0.3 nm in the visible range (430–850 nm) and the maximum time resolution of 2.0 μs. The software package developed allows: 1. (1) measuring of the chronograms of the relative concentrations of various active particles in parallel mode at eight spectral channels; 2. (2) generating impulse plasma modulation and measuring the microdynamics of the generation and annihilation of the active particles in the frame-by-frame mode (1024 points) in four parallel spectral channels, including the two corresponding background values. To shorten the measurement time and to improve the measurement accuracy of the particle annihilation kinetic characteristics in the interval between two stationary (long) pulses, it is proposed to form a series of probing (short) pulses. Some preliminary results are presented of the monitoring of the fluorine radicals (703.7 nm) relative concentration in the SF 6 gas r.f. plasma, containing as an actinometer a small amount (up to 5%) or argon (750.4 nm) at different discharge powers. Using the measurement results of the fluorine radicals, relative concentration in the pulse-modulated noble gas plasma obtained at monosilicon etching, the constants of the radical accumulation, as well as their life time values, are determined for the loaded and unloaded reaction chamber.

Hard, adherent amorphous carbon films were formed by condensation of evaporated carbon particles with additional noble gas ion bombardment of the growing film (ion assisted evaporation (IAE)). Ion energy, ion mass, angle of ion incidence and ion-to-atom arrival rate are the main parameters influencing the film growth. The effects of these parameters on the resulting structural (electron energy loss spectroscopy and density determination) and mechanical (Vickers hardness measurements) film properties were studied. In addition, a systematic investigation of the corrosion protection potential of the carbon IAE films was carried out. It could be shown that the corrosion protection and the hardness of the films are strongly dependent on the angle of ion incidence and the ion-to-atom arrival ratio. The latter quantity and the ion energy also affect the film density and structure. The experimental results are discussed in the context of simulations of ion-atom interactions. In general, the depth and volume of the activated region and the amount of transferred ion energy to the carbon matrix atoms mainly affect the film growth and the resulting film properties.

Amorphous carbon layers (a-C, a-C:H) with a hydrogen content between 3 at.% and 25 at.% were deposited by plasma decomposition processes, sputtering and evaporation. Their mass density values were obtained from a flotation method. The refractive index and absorption coefficient were calculated from spectrophotometric data. Special attention was paid to the Urbach tail and Tauc's plot absorption regions. The electrical conductivity was investigated in the temperature range T = 80–350 K. The conductivity values of all types of layers are discussed in terms of thermally activated conduction processes. In this sense all layers behave like semiconductors. For interpreting the conductivity values of the high gap layers, a Davis-Mott model with broad band tails was applied. However, this model was insufficient for fitting the conductivity data of samples with vanishing gaps. Reproduction of the conductivity values of these layers was possible in terms of a band model considering a structureless band at a position of 10–50 meV above the Fermi level. The conductivity of low gap samples (optical gaps around 0.3 eV) could only be fitted by a superposition of the conductivity laws following from both models. Fortuitously, the superposition of these functions yields a temperature dependence very similar to Mott's T − 1 4 law between 50 K and 300 K, which may be an explanation of this widely observed behaviour.

The optical constants of fine-grained diamond layers have been investigated by spectrophotometric means in the near-IR and visible spectral ranges. The layers were deposited by a microwave chemical vapour deposition technique on 〈100〉 and 〈111〉 oriented silicon substrates. For determining the optical parameters, measurements of the directed and diffuse reflectance and transmittance of the layer-on-substrate system have been carried out. The calculation of the optical constants has been accomplished by a curve-fitting procedure. For that purpose, a quadratic error function has been minimized by the method of conjugated gradients. To reduce the multiplicity of solutions, the refractive index has been assumed to increase with increasing wavenumber following a quadratic dispersion law, while the loss coefficient is assumed to increase exponentially with increasing wavenumber. The investigation of experimental spectra has shown that the method works successfully in application to layers with a surface r.m.s. roughness less than approximately 100 nm. For such layers, refractive index values have been obtained which are slightly lower than those of natural diamond, while the loss coefficients are much higher because of surface and bulk scattering.

The preparation of polycrystalline diamond particles and thin diamond films by deposition in the plasma discharge of a hollow cathode arc has been investigated. Although this discharge is known as a very simple and effective system for plasma generation, there has been little information about the growth of diamond by means of this method up to now. This type of discharge combines thermal and plasma dissociation of the reactant gases for diamond deposition. The temperature of the deposition area can be easily controlled by the electron current to the substrate and thus no auxiliary heating system is required, in contrast to many other diamond deposition methods. Furthermore, we assume additional decomposition of the reactant gases at the surface of the substrate due to the strong electron bombardment. As-deposited diamond particles and films were investigated by various electron microscopy methods, Raman spectroscopy and optical methods. They clearly show a polycrystalline structure with good crystallinity and quality. The diamond growth rate reaches about 2 μm h−1 on a deposition area of about 4 cm2.

In depositing thin carbon films by the r.f. sputtering of a graphite target in argon, an optimal parameter window was found in which it is possible to prepare adherent, IR-transparent, insulating, hard layers. Approximations for the sputtering process (total sputtering yield, energy of the sputtered carbon particles on the substrate) are demonstrated. A characteristic dependence of the film properties on the target voltage, an essential sputtering parameter, exists. In all cases, the target voltage influences the bombardment of the growing film by charged energetic particles. An anisotropic layer behaviour was established for more strongly absorbing films by three different methods of investigation. Finally, preliminary considerations concerning the film structure were made.

The optical properties of hard dc plasma deposited amorphous carbon layers have been investigated from the middle IR up to the visible spectral region. Refractive indices and absorption coefficient behaviour have been determined by means of spectral transmittance and reflectance measurements. The layers show a transparency window in the middle IR in the wavenumber range 1700 cm −1 v −1 . The refractive indices in the “window” region are between 2.1 and 2.3 with weak dispersion. IR-absorption losses have been discussed in terms of a dispersion model, considering the absorption detected to be caused by a superposition of Lorentz-lines and an Urbach-part. Planar and transverse conductivities of the layers have been determined at room temperature. In addition, the conductivity of representative samples has been investigated in dependence of the temperature in the range of 80 K up to 350 K. A correlation between the thus-obtained activation energies for thermally-activated hopping in the band tails and the Urbach parameters of the layers could be established.

A new method for optical thin film constant determination from spectrophotometric data is presented. The method combines features of single-wavelength methods as well as multiwavelength methods and thus represents a hybrid method specially designed for the analysis of amorphous thin film materials with more or less involved absorption behaviour, such as amorphous hydrogenated carbon (a-C:H), amorphous hydrogenated silicon (a-Si:H) and related materials. The unambiguity and continuity of solution contours are guaranteed without the postulation of any analytical dispersion law, by introducing specially constructed mathematical terms into the merit function to be minimized. The accuracy in determining refractive indices and film thicknesses is comparable to that achieved by curve-fitting methods. Weak inhomogeneities in film thickness may be taken into account.

The optical parameters n and k of i-C:H layers produced by microwave plasma deposition and from an ion-plating deposition system on silicon substrates are determined by T and R measurements in the IR range. A computer model is given; the multiple solutions, the influence of errors in experimental values and the absorption peaks of the i-C:H layers in the IR range are discussed.

The growth of device-worthy silicon crystals on insulating substrates would offer a new type of semiconductor technology. Lateral epitaxial growth is demonstrated for several types of structures using island configurations of silicon deposited either onto continuous or onto structure-etched SiO 2 . The crystallization of the deposited silicon islands was performed either by a large-area light pulse or by a zone melting process. With regard to the crystallinity and the flatness the best results were achieved using encapsulated island structures and the zone melting process.

The deposition of hydrogenated amorphous carbon films by an electron cyclotron resonance (ECR) microwave plasma and an ECR microwave ion beam source is described. Optical, electrical and mechanical measurements and different analytical methods are used for film characterization. The films deposited at a rate of about 200 nm min-1 develop a high electrical resistivity (109-1014 Ω cm), good IR transparency, an optical gap of about 1.7 eV and a hardness up to 30 GPa (measured on silicon substrates). Sputtering deposition experiments were performed with the aim of investigating the influence of the hydrogen on the layer properties as well as the possibilities of deposition on highly insulated substrates. Layers made by means of the sputtering deposition method indicated that hydrogen might be involved in the set-up of a metastable ion-assisted hydrogenated amorphous carbon.