High-power impulse magnetron sputtering (HiPIMS) drives thin-film growth through bursts of highly ionized material, but the microsecond-scale choreography of ion fluxes to the substrate - crucial for tailoring film properties - has eluded direct scrutiny. Here, we introduce microsecond chronometry using a magnetized quartz crystal microbalance (M-QCM) probe, which time-filters arriving ions via pulsed biasing synchronized to the discharge. This unveils, for the first time, the instantaneous flux of sputtered species during individual pulses, resolving dynamics unattainable by prior diagnostics. Across diverse HiPIMS regimes, we reveal that peak ion fluxes scale with average pulse power rather than current spikes, expose back-attraction trapping most ions near the target, and map how voltage-current waveforms dictate arrival timing. By deconvolving gated deposition rates, we reconstruct full temporal profiles, exposing subtle pulse-length dependencies that govern escape and transport. These insights illuminate ionization and transport in non-equilibrium plasmas, enabling precise control of ionized fluxes for advanced coatings in electronics and beyond. Our chronometric approach extends to other pulsed systems, bridging diagnostics with real-time plasma engineering.

The energy distribution of negatively and positively charged ions in a magnetron discharge is investigated. A zinc cathode operated in an argon/oxygen gas mixture is employed. The magnetron is operated in the pulsed mode with repetition frequencies of 10–30 kHz. Positively charged atomic O+, Ar+, and Zn+ ions, molecular O2+, ArO+, Ar2+, ZnO+, and ZnO2+, and doubly charged Ar2+ ions and negatively charged O−, O2−, ZnO−, and ZnO2− ions are observed. Negatively charged ions either form inside the plasma volume by electron attachment reactions or are sputtered from the negatively biased cathode and as such receive high kinetic energies corresponding to the cathode potential. The intensity of the negatively charged O− strongly depends on the plasma parameters, in particular, the repetition rate. Zinc oxide films are deposited at room temperature at repetition frequencies of 10–30 keV. The deposited films are characterized by means of scanning electron microscopy, x-ray diffractometry, photothermal deflection spectroscopy, optical and infrared ellipsometry, Fourier-transform infrared and Raman spectroscopy, and photoluminescence. These films are highly oriented along the surface normal and are highly transparent in the visible spectral region. The extracted optical bandgap and Urbach energy are about 3.3 eV and 62 meV, respectively.

This study presents the fabrication of highly photosensitive undoped zinc oxide (ZnO) thin films for vacuum ultraviolet (VUV) radiation detection, covering the wavelength range of 100–200 nm. ZnO films were deposited using hybrid pulsed reactive magnetron sputtering, assisted by ECWR (electron cyclotron wave resonance) plasma. Control of the ECWR power (PECWR), ranging from 0 to 380 W, played a crucial role in enhancing the films’ photoconductive properties. At PECWR = 200 W, the photosensitivity increased by 8 orders of magnitude compared to films deposited without ECWR assistance. This improvement was attributed to a sharp reduction in dark current due to lower defect density. Photoluminescence and cathodoluminescence spectra revealed a significant reduction in defect-related emissions for films deposited at PECWR = 200 W, confirming fewer intrinsic defects. Raman spectroscopy also showed a decrease in defect-related vibrational modes in the same films. Time-Resolved Microwave Conductivity (TRMC) measurements further supported these findings, demonstrating rapid recombination of charge carriers at 200 W, indicative of low trap densities. These results suggest that precise control of ECWR power allows for optimization of the defect concentration and crystallinity in ZnO films, paving the way for the development of high-sensitivity VUV photodetectors.

This study examines the two-dimensional (2D) spatial distribution of the ionized flux fraction (IFF) and total flux of sputtered species in a non-reactive high-power impulse magnetron sputtering discharge for a peak current density of approximate to 1.3 A/cm(2). Five magnetic configurations of the magnetron cathode, ranging from highly unbalanced to highly balanced, were systematically investigated. Flux measurements were performed using a quartz crystal microbalance with an electron magnetic filter. IFF was axially and radially scanned in the diffusion plasma in a plane normal to the target. These measurements resulted in comprehensive 2D maps of the metal ions' flux distribution within the region of particular interest, where the substrates are typically placed. The experimental findings are further compared and correlated with the modeled magnetic field distribution. Our study provides deeper insight into the impact of the magnets' arrangement on the thin film deposition process, offering potential benefits for a wide range of applications where tailored thin film properties are essential.

A pulsed reactive magnetron sputtering system with a tungsten target and a gas mixture of argon and oxygen was investigated as a source for the deposition of semiconductor WO3 thin films on soda lime glass substrates and on the glass with transparent conductive SnO2:F (FTO) electrode. The reactive sputtering process was performed in HiPIMS mode with low pulse repetition frequency fp ti 50-100 Hz and short pulse duration in HiPIMS discharge Ton = 100 mu s. The second mode investigated was the mid-frequency (MF) magnetron discharge with pulse frequency fp = 40 kHz and pulse length Ton = 15 mu s. The plasma parameters were investigated for both HiPIMS and MF modes using the planar RF probe operating at the frequency fprobe = 350 kHz and the grid QCM with biased collector electrode. Ion density ni and tail electron temperature (Te) were determined in both pulsed reactive magnetron sputtering discharge modes with time resolution. The maximum value ni ti 5 center dot 1017 m- 3 was found in the reactive HiPIMS mode, and the maximum value ni ti 7 center dot 1016 m-3 was found in the reactive MF (40 kHz) mode. The degree of ionization of sputtered particles in reactive HiPIMS was determined for different values of (QO2) and was found to be in the range of ri ti 0.1-0.3. The deposition rate determined by QCM in reactive HiPIMS was practically independent on (QO2), but in the case of reactive MF, the measured deposition rate decreased significantly with increasing (QO2). The WO3 films deposited in both modes have a predominantly monoclinic crystal structure. The light and dark conductivity and the light/dark conductivity ratio (Ld) were measured under dark conditions and UV light illumination. At higher (QO2), the maximum value of Ld ti 300 was found for MF deposited WO3 and the maximum value of Ld ti 30 was found for HiPIMS deposited WO3. The photoelectrochemical measurement of WO3 deposited on FTO electrodes confirmed the n-type conductivity, and these films functioned as photoanodes in photoelectrochemical cells. MF deposited WO3 films systematically exhibited slightly higher photocurrents than HiPIMS deposited WO3. It was shown that these optimum photocurrents for HiPIMS and MF were found at QO2 ti 80 sccm and could not be improved by further increasing of (QO2).

Cobalt nickel oxide films are deposited on Si(111) or fluorine-doped tin-oxide-coated (FTO) glass substrates employing a pulsed hollow-cathode discharge. The hollow cathode is operated with argon gas flowing through the nozzle and with O2 gas admitted to the vacuum chamber. Three different cathode compositions (Co20Ni80, Co50Ni50, and Co80Ni20) are investigated. Deposited and annealed thin films are characterized by X-ray diffraction, infrared (Raman) spectroscopy, and ellipsometry. As-deposited films consist of a single mixed cobalt nickel oxide phase. Upon annealing at 600 °C, the mixed cobalt nickel oxide phase separates into two cystalline sub-phases which consist of cubic NiO and cubic Co3O4. Annealed films are investigated by spectroscopic ellipsometry and the optical bandgaps are determined.

Recently, a novel approach of depositing metallic films with chemical vapor deposition (CVD), using plasma electrons as reducing agents, has been presented and is herein referred to as e-CVD. By applying a positive substrate bias to the substrate holder, plasma electrons are drawn to the surface of the substrate, where the film growth occurs. In this work, we have characterized the electron flux at the substrate position in terms of energy and number density as well as the plasma potential and floating potential when maintaining an unbiased and a positively biased substrate. The measurements were performed using a modified radio frequency Sobolewski probe to overcome issues due to the coating of conventional electrostatic probes. The plasma was generated using a DC hollow cathode plasma discharge at various discharge powers and operated with and without precursor gas. The results show that the electron density is typically around 1016 m−3 and increases with plasma power. With a precursor, an increase in the substrate bias shows a trend of increasing electron density. The electron temperature does not change much without precursor gas and is found in the range of 0.3–1.1 eV. Introducing a precursor gas to the vacuum chamber shows an increase in the electron temperature to a range of 1–5 eV and with a trend of decreasing electron temperature as a function of discharge power. From the values of the plasma potential and the substrate bias potential, we were able to calculate the potential difference between the plasma and the substrate, giving us insight into what charge carriers are expected at the substrate under different process conditions.

Semiconducting Fe2O3 thin films were deposited on SnO2:F (FTO) and Pt substrates by reactive high-power impulse magnetron sputtering combined with electron cyclotron wave resonance plasma (HiPIMS + ECWR). Fe2O3 films were fabricated either by sputtering from a single Fe target or by co-sputtering from an additional Sn target. Plasma parameters during co-sputtering were measured by an RF probe system enabling the comparison between HiPIMS + ECWR and only HiPIMS conditions used for the film deposition. As deposited Fe2O3 films were post-annealed in air at 450 degrees C and 650 degrees C, respectively. It was shown that as deposited Fe2O3 films were amorphous but became crystalline after post-annealing at 450 degrees C. Further increase of annealing temperature to 650 degrees C did not improve significantly the crystalline structure of the Fe2O3 film. All post-annealed Fe2O3 films exhibited photocurrents in the anodic region; generally, hematite films annealed at 650 degrees C exhibited higher photocurrents than those annealed at 450 degrees C. Films doped by Sn co-sputtering had higher photocurrents than films only doped by Sn diffusion during post-annealing from the FTO substrate. Hematite films on Pt substrate doped by Sn co-sputtering and post-annealed at 650 degrees C exhibited the highest photocurrents. It was verified by XPS analysis with ion sputtering depth profiling that Pt atoms also diffuse from the Pt substrate into the Fe2O3 film during the post-annealing at 650 degrees C and can, similar to Sn in the case of an FTO substrate, act as a dopant.

Among the numerous advantages of the high-power impulse magnetron sputtering (HiPIMS) technique, the most important is the enhanced ionization degree of sputtered species contributing to the film growth. Consequently, the quality of deposited thin films is highly improved. Still, the optimization process is challenging due to the complexity associated with the intricate transport of the sputtered species, ionized or neutrals. The scarce knowledge available on the spatial distribution of these species when operating a HiPIMS discharge makes the quantitative prediction of any deposition feature particularly difficult. In this paper, we discuss the influence of experimentally controllable quantities, such as gas pressure and target current density, on the transport of sputtered titanium in non-reactive (argon) HiPIMS, namely, on the behavior of metal atoms and metal ion fluxes intercepting the substrate. Systematic quantitative measurements were performed in a diameter normal plane on a circular planar target. Hence, the 2D spatial distribution of the ionized flux fraction (IFF) and the total flux of titanium sputtered particles (deposition rate) are evaluated by biasing a quartz crystal microbalance equipped with an electron magnetic filter. The wide range of parameters we examined allows us to predict and optimize the flux of sputtered species based on complete mapping of the IFF of sputtered particles.

The study is focused on the impact of different magnetic field configurations of a high-power impulse magnetron sputtering (HiPIMS) in a nonreactive mode on the film precursors. Ionized flux fraction and total flux deposited onto the substrate were measured with the magnetic quartz crystal microbalance probe placed in front of the target racetrack. Particularly, we investigated the degree of magnetron balancing and the geometry of the magnetic field above the Ti target surface (4 in. diameter), as crucial factors influencing the thin film deposition, for different HiPIMS pulse lengths. Three unbalanced (II type) magnetron configurations have been chosen for this study: two symmetric geometries—with a regular magnetic field (B parallel to the target about 80 and 35 mT) and one asymmetric (highly unbalanced) magnetron configuration with an intermediate magnetic field (B parallel to the target about 48 mT). The HiPIMS was operated keeping constant the peak current at 43 A for C0-E0 and C10-E0 B-field configurations and a lower value, 33 A, when operating in C10-E10 configuration. In addition to the peak current, the pulse frequency was kept constant at 100 Hz but the pulse length (power on-time, Ton) was varied from 50 up to 100 μs. Obviously, the pulse power and the average power continuously increase with the length of the pulse. The results reveal a significant difference in the trends of the deposition rate and ionized flux fraction reaching the substrate with respect to the degree of balancing of the magnetron. It was found that the ionized fraction of metal arriving at the substrate reaches its maximum for the pulse length between Ton ≈ 70–80 μs in both symmetric cases, with strong and weak magnetic fields. The ionized fraction of Ti atoms in the asymmetric configuration increased in all measured range with the pulse length and the growth rate has a smooth increase.

The high power impulse magnetron sputtering (HiPIMS) discharge brings about increased ionization of the sputtered atoms due to an increased electron density and efficient electron energization during the active period of the pulse. The ionization is effective mainly within the electron trapping zone, an ionization region (IR), defined by the magnet configuration. Here, the average extension and the volume of the IR are determined based on measuring the optical emission from an excited level of the argon working gas atoms. For particular HiPIMS conditions, argon species ionization and excitation processes are assumed to be proportional. Hence, the light emission from certain excited atoms is assumed to reflect the IR extension. The light emission was recorded above a 100 mm diameter titanium target through a 763 nm bandpass filter using a gated camera. The recorded images directly indicate the effect of the magnet configuration on the average IR size. It is observed that the shape of the IR matches the shape of the magnetic field lines rather well. The IR is found to expand from 10 and 17 mm from the target surface when the parallel magnetic field strength 11 mm above the racetrack is lowered from 24 to 12 mT at a constant peak discharge current.

A hollow cathode discharge with a CuNi (Cu50Ni50) cathode is operated inside a vacuum chamber with Ar gas flowing through its nozzle. O2 gas is admitted to the vaccum chamber. Typical Ar+O2 gas pressures are in the range of 2–50 Pa. The energy distribution of plasma ions is investigated with the help of energy-resolved mass spectrometry. Singly charged Ar+ and molecular O2+ ions are the most abundant ionic species. Deposition rate and heat flux to a substrate increase as function of discharge current. At high pressures, the deposition rate is further increased by the directional gas flow, which becomes more focused onto the substrate. Deposited and annealed thin films are analysed by X-ray diffraction and Raman spectroscopy. As-deposited films are composed of a mixed CuxNi1−xO cubic phase with a preferred (111) orientation. Upon annealing at 600 oC, the mixed CuxNi1−xO phase separates into two sub-phases composed of NiO and CuO. Annealed films display a photoelectrochemical (PEC) activity as a photocathode. The PEC activity deteriorates with time, however. This behaviour is related to the reduction of CuO to Cu2O.

A novel method for the preparation of Ni-Cu oxide catalysts—deposition on stainless steel meshes using hollow cathode plasma jet sputtering—was studied. This method allows the preparation of thin oxide films. Consequently, the whole volume of the active phase is readily accessible for the reactants and can be employed in the catalytic reaction due to the negligible effect of internal diffusion. As a result, the activity of our sputtered catalyst was seven times higher in ethanol oxidation and 61 times higher in toluene oxidation than that of the corresponding granular catalyst. Moreover, due to stainless steel meshes used as a catalyst support, the pressure drop across the catalyst bed was lower. Finally, the catalytic activity of the sputtered Ni-Cu oxide catalyst with Ni:Cu molar ratio of 1:1 in ethanol oxidation was 1.7 times higher than that of the commercial EnviCat® VOC-1544 catalyst, while the amount of the active phase in the catalyst bed was 139 times lower. The outstanding performance of the Ni0.5Cu0.5 catalyst was ascribed to the synergistic effect between the copper and nickel components.

A reactive high-power impulse magnetron sputtering system (HiPIMS) working in Ar + H2S gas mixture was investigated as a source for the deposition of iron sulfide thin films. As a sputtering material, a pure Fe target was used. Plasma parameters in this system were investigated by a time-resolved Langmuir probe, radio-frequency (RF) ion flux probe, quartz crystal monitor modified for measurement of the ionized fraction of depositing particles, and by optical emission spectroscopy. A wide range of mass flow rates of reactive gas H2S was used for the investigation of the deposition process. It was found that the deposition rate of iron sulfide thin films is not influenced by the flow rate of H2S reactive gas fed into the magnetron discharge although the target is covered by iron sulfide compound. The ionized fraction of depositing particles decreases from r ≈ 40% to r ≈ 20% as the flow rate of H2S, QH2S, changes from 0 to 19 sccm at the gas pressure around p ≈ 1 Pa in the reactor chamber. The electron concentration ne measured by the Langmuir probe at the position of the substrate decreases over this change of QH2S from 1018 down to 1017 m−3

We studied experimentally the condensation of Zn and Cu vapors from a high-temperature gas in an external weak constant magnetic field. We observed at all applied conditions, a chaotic time shift of the maximum of the size distribution function of dispersed particles. Simultaneously, a decrease in the width of the size distribution function of dispersed Zn particles from 40 nm (0 mT) to 10 nm (44 mT or 76 mT) was observed. The sizes of Zn particles were determined by laser probing. The sizes of dispersed Cu particles, determined by analyzing a substrate sample, were in the range of 10-400 nm without a magnetic field, and the range 30-320 nm in a magnetic field of 30 mT. The authors explain the observed results by arranging the dynamics of the spin pair of unpaired electrons of an atom from the gas phase and of an atom on the surface of a condensed particle in a magnetic field. Therefore, in a magnetic field, when an atom collides with a dispersed particle or condensation nucleus, the probability of creation of a singlet pair of spins of unpaired electrons is higher than that without a field.

An experimental setup has been developed that allows recording the flux of probing radiation scattered from dispersed particles in the 0 degrees direction. To suppress the beam passing through the swarm of dispersed particles a reference beam was used. The reference beam was formed from the probe beam and aligned in the registration plane with the beam passing through the swarm of particles. The Michelson interferometer was tested in an experimental setup to determine the sizes of dust particles of heterogeneous systems. It was shown that by placing a heterogeneous system in one of the arms of the interferometer, it was possible to register the scattered radiation at the angle 0 degrees. This facilitates calculation of the sizes of particles with the same accuracy over the entire size range. To verify the method the iron powder particles sized 50-63 mu m were used.