In this article, the experimental results obtained in our laboratory for the last 10 years and related to the reactive Ionized Physical Vapor Deposition (IPVD) processes are reviewed. Titanium oxide and titanium nitride thin films were chosen as case studies. The titanium-based thin films were synthesized from a pure titanium target sputtered in a mixture of argon and reactive gas (oxygen or nitrogen). Two IPVD processes were investigated namely (i) reactive magnetron sputtering amplified by a superimposed secondary inductively coupled plasma and (ii) reactive High-Power Impulse Magnetron Sputtering (HiPIMS). These researches were dedicated to the understanding of the plasma and plasma-surface interaction chemistries by using advanced plasma diagnostic techniques such as energy-resolved mass spectroscopy, time-resolved emission and absorption spectroscopy. The relationships between the plasma chemistry and energetics and the properties of the thin films are emphasized.

We continue the research of low-pressure capillary discharge lamps of 500 μm in radius in Ar/Hg, Kr/Hg and Xe/Hg mixtures. In the previous paper, an experimental approach which combines the optical emission spectroscopy (OES) and tomographic methods was developed to study the capillary discharge. The present work is focused on interpretation of the tomographic reconstruction results for understanding the physical processes occurring in a capillary plasma. Analyzing the results of reconstruction, it was concluded that the radial profiles of Ar, Kr and Xe emission coefficients are in a good agreement with the Schottky theory. According to the Schottky model, ionization processes in plasma are balanced by electrons and ions transfer to the wall due to ambipolar diffusion. Using the Schottky model, the electron temperature in an Ar/Hg capillary lamp was estimated. The value of the temperature was higher in comparison with that in a large-scale Ar/Hg discharge. A simplified model describing the excited atomic states kinetics is analyzed. This model agrees with all radial profiles of emission coefficients, obtained by using a tomography approach, except one for mercury line of 546.07 nm in the Ar/Hg capillary lamp. We suppose that the simplified model did not include the processes which were important for the mercury population balance in Ar/Hg mixture. It was proposed that the transfer of high-excited mercury atoms may play an appreciable role in the Ar/Hg capillary discharge.

A self-consistent kinetic model was developed in order to study the production of active species in Ar-O2 surface-wave microwave plasmas with a relatively small N2 addition. It is shown that the Ar-O2-N2 mixture produces efficiently the same active species as an Ar-O2 discharge, including oxygen atoms, metastable O2(a1∆g) molecules and the VUV emitting Ar(4s) states. Furthermore, active N-containing species are additionally produced, in particular N atoms and NO ground-state and excited molecules, which makes the ternary mixture very interesting for numerous plasma applications.

The present paper shows for the first time in the literature a complete 2D simulation of the ozone production in a DC positive multi-tip to plane corona discharge reactor crossed by a dry air flow at atmospheric pressure. The simulation is undertaken until 1 ms and involves tens of successive discharge and post-discharge phases. The air flow is stressed by several monofilament corona discharges generated by a maximum of four anodic tips distributed along the reactor. The nonstationary hydrodynamics model for reactive gas mixture is solved using the commercial FLUENT software. During each discharge phase, thermal and vibrational energies as well as densities of radical and metastable excited species are locally injected as source terms in the gas medium surrounding each tip. The chosen chemical model involves 10 neutral species reacting following 24 reactions. The obtained results allow us to follow the cartography of the temperature and the ozone production inside the corona reactor as a function of the number of high voltage anodic tips.

Results of computer simulations describing an interaction between a low-temperature multicomponent plasma and an immersed metal substrate are presented. For this purpose, computer model of volume processes in a DC glow discharge in Ar-O2 mixture and a particle model of plasma-solid interaction were created. The interaction is studied not only in case when a constant value of voltage bias on the immersed substrate is kept, but also when sinusoidal voltage bias is applied. A pressure dependence of the sheath region in electronegative plasma is shown, too.

In radiofrequency (RF) helicon discharges the electromagnetic power is transferred from the RF field irradiated by the antenna to the plasma medium by means of plasma-wave coupling of the electromagnetic wave with the electrons. For the common industrial frequencies of tens of MHz, and for typical pressures of few Pascals, the power deposition occurs mostly at the edge of the discharge. In these conditions, ionization and electron heating occur in a layer close to the chamber walls, where a consistent fraction of the plasma is rapidly lost by diffusion toward the surface. The remaining fraction of plasma diffuses inward toward the center of the discharge, setting up a uniform and almost flat density profile, used in applications. A one-dimensional model considering both the plasma-wave coupling of the electrons with the RF wave and the macroscopic transport of ions and neutrals along the radial dimension of a cylindrical processing chamber has been derived and used to evaluate the profiles at equilibrium. The model has been validated through Langmuir probe measurements in helicon processing chambers. The numerical model has then been used to study the power-coupling behavior of the discharge when the pressure of the neutral gas is decreased. When the Knudsen number of the neutral gas approaches unity and in conditions of slightly magnetized discharge, the power deposition shifts from being edge-localized to center-localized, thus reducing the particle fluxes toward the walls and increasing the efficiency of the coupling.

A hydrodynamic model was developed to simulate the flow and the heat transfer with the gas/plasma system produced by a microwave-driven (500–900 W at 2.45 GHz) axial injection torch, running in atmospheric pressure helium at 3–9 L min−1 input gas flows. The model solves the Navier-Stokes’ equations, including the effect of the plasma upon the momentum and the energy balance, in order to obtain the spatial distributions of the gas velocity and temperature. The model predicts average gas temperatures of 2500–3500 K, in the same range of those obtained by optical measurements. Simulations show that the plasma influences the gas flow path and temperature, promoting an efficient power transfer.

The laser-induced fluorescence spectroscopy on a micro-flow discharge with water electrode is carried out in order to investigate OH radicals. The branches P2(6), P1(4) and P2(3) of X2Π, ν′′ = 0−A2Σ, ν′ = 1 transition are used. Laser-induced fluorescence is used in order to estimate the density of OH radicals and density of water vapor in a core of the plasma. Sputtering yield of H2O from the liquid electrode is calculated based on experimental data. It is revealed that plasma core consists of 8–10% of water in both Ar and He discharges. The density of OH radicals in the micro-flow He plasma is higher than in the glow discharge with liquid electrode and in Ar micro-flow discharge due to constriction of the positive column and different mechanism of the OH radical production.

The rate coefficient of the ternary association reaction H++2H2→H3++H2$ {\mathrm{H}}^{+}+2{\mathrm{H}}_2\to {\mathrm{H}}_3^{+}+{\mathrm{H}}_2$ has been measured at a temperature of 11 K using a 22-pole ion trap. The measurements were made over the density range of 0.5–10 × 1013 cm−3 using normal hydrogen (with 1/4 p-H2 and 3/4 o-H2). We measured an apparent binary reaction rate coefficient and from the obtained linear dependence on the hydrogen density we calculated the ternary reaction rate coefficient k3 = (3 ± 1) × 10−29 cm6 s−1. From the measured data we can deduce that there exists very slow radiative association with the rate coefficient of the order of kr ≲ 3 × 10−16 cm3 s−1 at 11 K.

New flowing afterglow apparatus, Cryo-FALP, was built to study ternary Collisional-Radiative Recombination (CRR) of Ar+ ions with electrons in He/Ar afterglow plasma at temperatures 40–200 K. The obtained ternary recombination rate coefficient at 57 K is KCRR = (3 ± 1) × 10−17 cm6 s−1. It is the first time that the KCRR was measured below 77 K. The measured temperature dependence KCRR ~ T(−4.5 ± 0.4) is in a good agreement with theoretical prediction.

The potential of simultaneous to etching deposition for surface roughness control is investigated with a stochastic modeling framework for morphology evolution in (2+1) d. It is predicted that ion-driven etching under simultaneous deposition of etch-inhibitors (e.g., impurities coming from the wafer surroundings, the reactor walls, or the plasma bulk) not only induces roughness formation with a linear dependence on time, but can also induce periodic dots on the surface. The surface roughness can be controlled by regulating the amount of etch-inhibitors.

Silicon carbide films were deposited at two deposition temperatures 350 °C and 450 °C by means of ECR plasma reactor with two gas mixtures: (1) gas mixture, SiH4 (5 sccm), CH4 (14 sccm), Ar (6 sccm), NH3 (2 sccm) and (2) gas mixture SiH4 (5 sccm), CH4 (14 sccm), H2 (6 sccm), NH3 (2 sccm). The concentration of species in the SiC films was determined by Rutherford backscattering spectrometry (RBS) and elastic recoil detection (ERD) analytical method simultaneously. Chemical compositions were analyzed by infrared (IR) spectroscopy. Photoluminescence (PL) spectra were measured at 300 K. The RBS and ERD results showed that the concentrations of Si and C in the films are practically the same. The concentration of hydrogen decreased from 30 to 22 at.% with an increasing sample deposition temperature. The films contain a small amount of nitrogen and oxygen. IR results showed the presence of Si-C, Si-N, Si-H, C-H and Si-O bonds. PL results showed the decrease of the PL intensity with an increasing sample deposition temperature.

This paper investigates the performance of hydrogenated amorphous carbon (a-C:H) films as protective coatings for a forming tool made from AISI M2 steel coated with a titanium nitride (TiN) PVD commercial layer. The samples were initially cleaned in ultrasonic baths and subsequently in a plasma ablation procedure. Films were then deposited by plasma immersion ion implantation using 91% of acetylene and 9% of argon at a total pressure of 5.5 Pa. Samples were biased with high voltage negative pulses, P (T = 3.33 ms, pulse on-time: 0.03 ms, pulse off-time: 3.30 ms and application rate: 299 Hz) with amplitudes varying from 1.000 to 4.000 V. The chemical structure and composition of the films were evaluated by infrared spectroscopy. The roughness was determined by profilometry while the surface topography and morphology were investigated by atomic force microscopy and scanning electron microscopy, respectively. The friction coefficient was determined by the ball on disk technique. A decrease in the proportion of C-H and O-H groups was observed while the concentration of dangling bonds enhanced with increasing P. Sharp structures were detected on the film surface affecting roughness in two different ways: it increased with enhancing pulse magnitude in the smoothest substrate (AISI M2) and decreased in the roughest one (AISI M2-TiN). The best tribological result was found for the sample deposited with 3.600 V of bias onto TiN-AISI M2 steel.

In a trend for sustainable engineering and functionalization of surfaces, we explore the possibilities of gas phase processes to deposit nanocomposite films. From an analysis of pulsed plasma polymerization of maleic anhydride in the presence of nanocellulose whiskers, it seems that thin nanocomposite films can be deposited with various patterns. By specifically modifying plasma parameters such as total power, duty cycle, and monomer gas pressure, the nanocellulose whiskers are either incorporated into a buckled polymer film or single nanocellulose whiskers are deposited on top of a polymeric film. The density of the latter can be controlled by modifying the exact positioning of the substrate in the reactor. The resulting morphologies are evaluated by optical microscopy, AFM, contact angle measurements and ellipsometry.

In this work, we have investigated the influence of the magnetic field configuration during magnetron sputtering of WO3 in order to establish the ion flux-film structure relationship. An asymmetric bipolar pulsed DC magnetron sputtering (PDMS) was used with two magnetic field configurations: balanced (BM) and unbalanced (UMB) magnetic configurations. Ion Energy Distribution Functions (IEDFs) of the main ion populations (Ar+, O+) were recorded. The IEDFs are broad with, in addition of the thermalized distribution around 2 eV, two peaks with available ion kinetic energy up to 40–100 eV associated with the positive part of the pulse. Comparing the BM and UBM data, we calculated an increase by a factor of 5 of the ionic current while the average energy per ion was kept constant (~44 eV). X-ray diffraction demonstrates the influence of the magnetic configuration on the coating phase constitution. The films are crystallized in the WO3 monoclinic phase with preferential orientations along the c axis using the BM configuration and along the a axis using the UBM one’s. On the other hand, it has been demonstrated that the grain size increases with the thickness using the BM configuration (up to 18 nm) while it remains constant using the UBM one’s (~7 nm).

Plasma polymerized tetraethoxysilane (ppTEOS) thin films deposited on quartz crystal microbalance (QCM) electrode were used as sensitive layer for the detection of a number of volatile organic compounds (VOCs) such as methanol, ethanol, acetone and chloroform molecules. Their sensing properties were examined by measuring the resonance frequency shifts (∆f) of QCM which are due to additional mass loading. The results showed that ∆f of QCM were found to be linearly correlated with different vapor pressure of analyte. The sensor showed good reproducibility and reversibility. The ppTEOS film is found to be highly sensitive to methanol vapor than other vapors. Fourier transform infrared spectroscopy (FTIR) analysis showed the presence of CHx peaks around 2962 cm−1 making the elaborated layer more porous and low dense, resulting in the promotion of VOC vapor diffusion into the film.

Small plasma spheroids are evidenced and analyzed in front of the electrodes of a capacitively-coupled radio-frequency discharge in which dust particles are growing. These regions are characterized by a spherical shape, a slightly enhanced luminosity and are related to instabilities induced by the presence of dust particles. Several types of behaviors are identified and particularly their chaotic appearance or disappearance and their rotational motion along the electrode periphery. Correlations with the unstable behavior of the global plasma glow are performed. These analyses are obtained thanks to high-speed imaging which is the only diagnostics able to evidence these plasma spheroids.

Methods to induce non-thermal atmospheric pressure plasma filaments are presented with related properties for micro, streamer and prevented spark discharges, respectively, induced in planar Dielectric Barrier Discharges with one electrode covered by dielectric material (mono-DBD) or point-to-plane Corona. Two mechanisms of nano-particles formation are depicted from aerosol size distributions and TEM analysis. 0.1–10 mJ prevented spark discharges produce 10–100 nm droplets ejected from melted craters as well as nucleated primary particles and subsequent 10–100 nm agglomerates, by nucleation and coagulation in expanding vapor jets. With smaller energy per filament, 0.1–10 μJ micro-discharges and 0.1–100 μJ streamers, the initial local vapor fluxes emitted from spots of interaction between plasma filaments and electrodes are reduced. Subsequent smaller primary particle density limits the local coagulation in the vapor plume since 2–10 nm non-agglomerated crystalline metal nano-particles are produced in mono-DBD with Au, Ag and Cu electrode. Besides, the evolution of the aerosol size from primary nano-particles to agglomerates with transit time suggests slow coagulation of these primary metal particles in mono-DBD. Aerosol properties depend on the energy per filament and on the electrode. The final size is controlled by plasma parameters and transit time in and after the plasma. The aim is to underline emerging applications of atmospheric pressure plasmas for the production of tailored particles with tunable size, composition and structure with non-thermal plasma filaments to control the resulting properties of nano-powders and materials. Production rates and related energetic yields are compared.

Two different atmospheric pressure microplasma systems are discussed and used for the synthesis and surface engineering of a range of nanomaterials. Specifically a gas-phase approach from vaporized tetramethylsilane has been used to synthesize silicon carbide nanoparticles with diameters below 10 nm. A different microplasma system that interfaces with a liquid solution has then been used for the synthesis of surfactant-free electrically stabilized gold nanoparticles with varying size. A similar microplasma-liquid system has been finally successfully used to tailor surface properties of silicon nanoparticles and to reduce graphene oxide into graphene. The synthesis and surface engineering mechanisms are also discussed.