Ar Pressure Research Articles

Characterization of MoS2:Nb sputtered thin films. An application as hole transport layer in Cu2ZnSnS4/Si tandem solar cells

MoS2:Nb films deposited by radio-frequency magnetron sputtering are investigated in view of their application in infrared (IR)-transparent contacts for tandem photovoltaic devices.This material is already known to give a good electrical contact with p-type chalcogenide semiconductors, which are typically grown onto opaque molybdenum metallic contacts and a MoS2 layer spontaneously forms at the back interface during the on-top semiconductor growth. Our study explores a different approach, which involves the direct growth of IR-transparent MoS2:Nb films via sputtering inside complete photovoltaic devices, like Cu2ZnSnS4 (CZTS)-based single junction solar cells and CZTS/Si tandem devices. Films deposited at different sputtering pressures are compared by analysing their microstructure, morphology, chemical composition, optical and electrical properties. The effects of post-deposition sulfurization treatments are also investigated. We find that MoS2:Nb films deposited at around 0.1 Pa exhibit compactness but show a notable sulfur deficit ([S]/[Mo]≈1.4), a significant sub-bandgap optical absorptance and lack of crystallinity. Increasing the Ar pressure to 1 Pa raises the [S]/[Mo] ratio to 2.2, yielding crystalline films with good IR-transparency, although with a porous morphology. Despite 0.5 wt% Nb-doping of the sputtering target, the as-deposited films demonstrate n-type conductivity likely due to uncontrolled impurities and intrinsic defects. Ultraviolet Photoemission Spectroscopy measurements suggest that films’ work function higher than 5 eV can be obtained with a post-deposition sulfurization, making these materials suitable as Hole Transport Layer in photovoltaic applications. A similar increase in work function is expected in the CZTS/MoS2 junctions, since the sputtered MoS2:Nb films undergo a sulfurization process needed to obtain the overlying polycrystalline CZTS absorber.CZTS solar cells produced with sputtered MoS2 and Transparent Conductive Oxides contacts on glass substrates, despite plagued by severe adhesion problems, show the potentiality to give efficiencies comparable to reference devices with standard Mo back contact. Fabrication of CZTS/Si tandem devices on textured silicon bottom cells yields a maximum efficiency of 4.4 %, primarily hindered by the low quality of the CZTS film on textured substrates. Nonetheless, optoelectronic characterizations based on both spectrophotometric and quantum efficiency measurements confirm a good IR transparency of the MoS2-based intermediate contacts and the desired electrical behaviour.

Vibrational relaxation of HOD by collisions with Ar atoms.

Vibrational relaxation of HOD(v12, v3) molecules by collisions with Ar was studied at 298K (v12 denotes coupled bending, v2, and OD stretching, v1, vibrational modes and v3 denotes OH stretching mode). The vibrationally excited HOD molecules were generated by exothermic abstraction reactions of OD radicals with 13 different RH reactants and observed by infrared emission from a fast-flow reactor as a function of Ar pressure and reaction time. State-specific relaxation rate constants were obtained by comparison of the time evolution of the experimental vibrational distributions with numerical kinetic calculations for vibrational populations. The relaxation mechanism was based on the relaxation scheme of H2O studied earlier with the addition of specific channels for HOD(v12, v3). Unlike H2O, energy in stretching and bending vibrations of HOD cannot be separated due to close ν1 and 2ν2 energies, which leads to fast collisional equilibration between these Fermi-resonant levels. For relaxation of the only pure bending state (10), a rate constant of (1.5 ± 0.3) × 10-13cm3molecule-1s-1 was obtained. The relaxation rate of higher v12 states linearly increases with quantum number and very likely includes transfer of population from OD stretch levels, v1, to a lower energy bend level. The average rate constants for the loss of population from (01), (02), and (03) stretching states are (1.1 ± 0.3) × 10-14, (3.2 ± 1.0) × 10-14, and (5.6 ± 1.2) × 10-14cm3molecule-1s-1, respectively.

Oxidation resistance and thermal stability of (MoZrHfTaNb)-Si-B coatings deposited by HIPIMS method with different Ar pressure

The influence of argon pressure on the structure, mechanical characteristics, oxidation resistance, and thermal stability of (MoTaNbZrHf)-Si-B coatings deposited by HIPIMS method using a composite target based on high-entropy (MoZrHfTaNb)Si2 silicide and (MoZrHfTaNb)B2 boride was studied. Coatings deposited at Ar pressure of 0.1–0.2 and 1.3–2.2 Pa had a dense, defect-free structure. Increasing the Ar pressure to 37–42 Pa led to the formation of a coating with a columnar structure, while, according to X-ray diffraction and transmission electron microscopy, all coatings were amorphous. Increasing the Ar pressure from 0.1 to 0.2 to 37–42 Pa led to a magnifying the growth rate of coatings in 2.5 times. All coatings were characterized by a similar hardness of 14–15 GPa. The elastic modulus and elastic recovery decreased from 196 to 178 GPa and from 40 to 34 % when the argon pressure increased from 0.1 to 0.2 to 37–42 Pa, respectively. The coatings successfully resisted oxidation at temperatures of 1100 °C and 1300 °C. The protective properties of the coatings are due to the formation of a dense oxide film based on a-Si:B:O amorphous phase with crystallites of the m-HfO2, m-ZrO2, m-Nb2O3, o-Ta2O5, t-ZrSiO4 and t-HfSiO4 phases. Heating in a TEM column showed that the coating deposited at an Ar pressure of 0.1–0.2 Pa crystallizes immediately upon reaching a temperature of 700 °C with the release of predominantly the h-MoSi2 phase. Crystallization of the coating obtained at an Ar pressure of 37–42 Pa also occurs at 700 °C, but only during long-term exposure and is accompanied by the precipitation of the h-Ta5Si3 and t-Nb5Si3 phases. Thus, it has been shown that by increasing the gas flow rate, the productivity of sputtering in the HIPIMS mode can be increased without a significant loss in hardness, oxidation resistance and thermal stability of coatings.

Effects of pulse time offset between Cr and Zr dual cathodes in closed-magnetic-field unipolar high-power impulse magnetron sputtering

Two cathode (target) materials, Cr and Zr, were paired in a closed-field magnetron dual-cathode configuration and used in unipolar high-power impulse magnetron sputtering (HiPIMS). Two pulse widths (pulse-on durations) and various pulse-time offsets between the negative-voltage pulses of the Cr and Zr targets were investigated by setting the synchronization delay between the HiPIMS power supplies of the two targets at two different Ar pressures. Several trends were observed by analyzing the waveforms of the target discharge current, target discharge voltage, and substrate current. The closed-magnetic-field dual-cathode configuration significantly enhanced the HiPIMS discharge efficiency of the Zr target at all pressures; however, the enhancement for the Cr target was considerably lower. The ion fluxes toward the substrate were influenced by two competing mechanisms. The charged species generated from the previous pulse on one target could be attracted by the subsequent pulse of the adjacent target as a preionized medium to enhance the HiPIMS discharge. However, the fraction of the previously emitted ion flux toward the substrate could be reduced. When a shorter pulse width of 70 μs was applied, the ion flux that reached the substrate was mainly affected by the pulse power of the Zr target, and delaying the pulses of the Cr target with a relatively lower ion yield can achieve a higher ion flux toward the substrate. Increasing the pulse width significantly increased ion fluxes emitted from both the Cr and Zr targets, increasing the total ion flux toward the substrate. The study indicates that for the Cr and Zr dual cathode pair, a pulse time offset of one pulse width plus more than approximately 200 μs would be the most efficient way to obtain the highest ion fluxes toward the substrate and achieve a better film quality.

The role of carbon capping and Ar pressure on SiC surface degradation during high temperature annealing

High temperature annealing (>1600°C) is commonly employed to activate dopants and recover the SiC lattice after ion implantation. Despite extensive studies monitoring surface roughness after annealing, a lack of understanding persists on how the carbon-cap (C-cap) effectively protects the SiC surface and prevents Si sublimation. This study investigates the role of the C-cap and ambient Ar pressure on SiC surface degradation. 4H-SiC wafers were implanted with 60 keV 1x1015 cm−2 Al+ at 700°C and annealed from 1650°C to 1950°C with a pyrolyzed C-cap. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) were used to study the evolution of the C-cap and SiC surface. The C-cap impacted the surface degradation morphology, from step-bunching to surface pitting above 1750°C, resulting in disordered graphite that does not conform or grow uniformly at the SiC surface. This is dramatically worsened at reduced Ar pressure. No Si accumulation was observed in the C-cap or at the interface, suggesting the C-cap is not a diffusion barrier to Si sublimation under our conditions. It is proposed that when a cap is present, the limiting step for SiC degradation is related to the crystallization and diffusion of C atoms as they form graphite, more than Si sublimation.

Deposition and nanoindentation study of a novel TiNi/Ag bi-layer shape memory film

Compositions, surface morphologies and mechanical properties of a novel designed TiNi/Ag bi-layer film grown by DC magnetron sputtering at various processes have been investigated. Ar pressure and sputtering power had significant effects on quality and composition of TiNi/Ag bi-layer films. The TiNi/Ag bi-layer film processed by sputtering under high Ar pressure (0.36 Pa) was porous, while better density films can only be obtained at low pressure (0.12 Pa). The composition of TiNi/Ag bi-layer films can be adjusted by sputtering power. The load-displacement curves show the multiple “pop-ins”along nanoindentation loading, as indentation depth does not exceed the pure Ag film thickness (∼340 nm). At the maximum loading of 140 mN, martensitic transformation induced by nanoindentation in TiNi/Ag bi-layer films was not found, and depth recovery ratio was 39%. Moreover, based on the load displacement curve analysis, the hardness and elastic modulus values of TiNi/Ag bi-layer films were 4 ± 0.2 Gpa and 79 ± 2 Gpa, respectively. Comparing with martensitic phase of single-layer TiNi thin films at room temperature, the coexistence of parent phase and martensitic phase of TiNi/Ag bi-layer films were mainly due to strong confinement effect of Ag layer deposition on TiNi thin film. The residual stress calculated by using conventional sin2ψ method was around −0.458 GPa. The present study provided an important theoretical basis for the preparation of TiNi/Ag bi-layer film with higher quality and performance.

Spatial confinement offered by a blocker on the laser-induced breakdown spectroscopy of Ti plasma

Spatial confinement effects offered by a blocker on the laser-induced plasma parameters of titanium (Ti) are evaluated using the Optical Emission Spectroscopy technique. Nd:YAG (1064 nm, 10 ns) laser is used as an irradiation source. To observe the spatial confinement effects, an Al blocker at different distances of 4, 6, and 8 mm from the target is placed along the plume path. All the measurements are performed under the Ar environment at different pressures. It is observed that with increasing laser irradiance plasma parameters such as excitation temperature (Te) and electron number density (ne) increase, whereas it is vice versa true for increasing blocker distances. Without the blocker, the maximum values of Te and ne are about 7000 K and 1.4 × 1018 cm−3, respectively, at an Ar pressure of 50 Torr. A significant increase in emission intensity along with Te ≈ 9810 K and ne ≈ 2.2 × 1018 cm−3 is achieved in the presence of blocker. The results show that spatial confinement is responsible for the enhancement of Te and ne, which is attributed to the increased collisional frequency of plasma species after compression by shockwaves. The ablation pressure and shock pressure are also analytically evaluated and vary from 0.15 to 0.25 GPa and from 0.1 to 0.2 GPa, respectively, with increasing laser irradiance. With increasing blocker distances from 4 to 8 mm, the work done by reflected shockwaves to compress the plume varies from 0.02 to 0.002 mJ.

Effect of Ar pressure on phase transition characteristics and charge transport mechanism in VO2 films grown by RF sputtering of V2O5

In this study, we report the growth and characterization of VO2 films deposited on YSZ (001) substrate employing RF magnetron sputtering of vanadium pentoxide (V2O5) target in pure Ar gas ambient. The VO2 film growth has been carried out at ∼700 °C for ∼15 min at ∼100 W RF power with a flow rate of ∼20 sccm at Ar gas deposition pressure of ∼3, ∼6, ∼20, and ∼40 mTorr. x-ray diffractometry and Raman spectroscopy show that the nearly pure VO2 phase achieved at lower Ar pressure, e.g., ∼3 and ∼6 mTorr transform into a multiphase V-O system at ∼20 and ∼40 mTorr. This pattern is also supported by the electrical transport measurements through the occurrence of hysteretic IMT in films grown at ∼3 and ∼6 mTorr and the absence of this signature in these films deposited at ∼20 and ∼40 mtorr Ar pressure. The most pronounced with the strongest hysteresis is seen in the Y6 film, and therefore, the optimum growth pressure in the present study is ∼6 mTorr. The suppression of IMT in Y20 and Y40 is attributed to the appearance of other V-O phases, which smear out the phase transition. The activation energy of the insulating phase is estimated from the Arrhenius fit to the ρ-T data is found to be ∼0.223 eV at ∼3 mTorr Ar pressure which increases to ∼0.311 eV for ∼6 mTorr film in the cooling cycle. The low temperature (120K≤T≤300K) transport conduction in all VO2 films is governed by Efros-Shklovskii’s variable range hopping (ES-VRH) mechanism with a systematic relation between growth conditions and phase transition characteristics. Thus, Argon gas pressure plays a critical role in growth and brings out the feasibility of VO2 films growth by RF sputtering of oxide V2O5 target under Argon ambient only.

Bi doped LaOCl and LaOF thin films grown by pulsed laser deposition

Thin films of Bi3+ doped LaOCl and LaOF phosphors prepared via the pulsed laser deposition (PLD) technique in vacuum and different argon (Ar) pressures were compared in order to assess their luminescence properties. All peaks of the X-ray diffraction patterns of the films were consistent with the tetragonal structure of the LaOCl and LaOF, but in the case of LaOF the signal was weaker and not all peaks were present, suggesting some preferred orientation. Photoluminescence measurements revealed that the films exhibited emission around 344 nm for LaOCl:Bi and 518 nm for LaOF:Bi under excitations of 266 nm and 263 nm, respectively. The luminescence from the LaOF:Bi sample was less intense compared to the LaOCl:Bi sample prepared under the same conditions, which was also the case for the powder samples. The amount of ablated material present on the substrate was much less for LaOF:Bi compared to LaOCl:Bi, which is attributed to the greater bandgap and hence weaker absorption of the laser pulses for LaOF:Bi. Therefore phosphors based on LaOCl as the host material were found to be preferable over LaOF under the PLD conditions used in this study.

EFFECT OF ARGON WORKING GAS PRESSURE ON MECHANICAL STRESSES IN Mo/Si MULTILAYER X-RAY MIRRORS

By the method of X-ray tensometry (=0.154 nm), the dependences of residual stresses in Mo/Si multilayer Xray mirrors (MXMs) obtained by direct-current magnetron sputtering were studied as a function of the sputtering Ar pressure in the range of 1…4 mTorr. It is shown that an increase in pressure is accompanied by an increase in stresses from ~ 0.4 to ~ 0.8 GPa for a group of mirrors with periods near 7 nm and from ~ 0.9 to ~ 1.6 GPa for a group of mirrors with periods near 14 nm. The angles of texture misorientation for Mo crystallites were measured as a function of argon pressure. Mechanisms have been proposed to explain the reasons for the increase in stresses.

Power spectral density analysis to investigate morphology of Ni films

Ni thin films grown by thermal evaporation and sputtering under different deposition conditions are characterised by structural and morphological properties using X-ray diffraction (XRD) and atomic force microscopy (AFM) techniques. XRD results suggested the growth of polycrystalline face-centred cubic Ni phase for all the samples. Morphological characteristics of the films were compared by analysing AFM data for root mean square roughness, height–height correlation function and power spectral density (PSD) measurements. Applying fractal and k-correlation fitting models to the PSD data, different morphological parameters are quantified. The study suggested that Ni films grown at higher substrate temperature (∼150 °C) by thermal evaporation and at low Ar pressure (∼0.2 Pa) by sputtering techniques yielded films of small surface roughness with a Brownian fractal self-affine surface.

Preparation and characterization of SbSeI thin films

Metal chalcohalides are promising candidates for next-generation technologies that include energy conversion, information storage, and quantum computing. Among them, antimony selenoiodide (SbSeI) has received rising interest for different optoelectronic devices, including photovoltaics, due to its bandgap energy, strong optical absorption, stability, and earth abundant, low-cost, and low toxicity constituents. In this work, SbSeI thin films were prepared through a two-step process. At first, antimony selenide (Sb2Se3) thin films were deposited at 300 °C (Sb2Se3-300) and at room temperature (Sb2Se3-RT) onto molybdenum covered soda-lime glass substrates by a magnetron sputtering method. The formation of SbSeI thin films was performed by isothermally annealing the as-deposited Sb2Se3 thin films in sealed quartz ampoules in the atmosphere of antimony iodide (SbI3) with the presence of 100 Torr of argon pressure. The influence of the annealing temperature and time during the iodization of different types of substrates on the morphology and composition of SbSeI thin films was investigated. The well-oriented and dense single-phase SbSeI thin films with stoichiometric composition and single-crystal micro-columnar structures were achieved by annealing Sb2Se3-RT in SbI3 atmosphere at 250 °C for 5 min under 100 Torr of Ar pressure. The room temperature photoluminescence (RT-PL) of SbSeI exhibited a broad asymmetric PL band with a maximum at 1.67 eV. The low-temperature (T = 8 K) PL study of SbSeI showed a broad and asymmetric PL band at 1.4 eV, being quite distant from the bandgap. This PL band at 1.4 eV with obtained small thermal quenching activation energy of 12.7 meV is proposed to originate from the deep donor-deep acceptor pair (DD-DA) recombination.

Self-consistent modeling and analysis of spatial homogeneity of pure Na and Na−Ar mixture resonance photoplasma in a gas cell for Voigt profile

A self-consistent modeling of the resonance photoplasma in pure Na and Na−Ar mixtures with spatial homogeneity of photoexcitation of the resonance levels of Na in the volume of a cylindrical gas cell has been carried out. The Voigt line shape and the collision broadening of the D1 and D2 lines of Na were considered. The main photoplasma parameters were calculated for the Na pressure PNa=0.0045−0.165 torr, the PAr/PNa=0 and 10k (k = 1, 2 and 3) values and the gas temperature of 680 K at the pumping resonance radiation flux density F = 40 W/(m2nm). It has been established that the electron density Ne and temperature Te increase non-linearly with the growth of the PNa and reach, respectively, 6.4·1018 m−3 at PNa=0.165 torr and PAr/PNa=100 and 0.28 eV for the pure Na photoplasma. Herewith, the dependence of Te on the Ar pressure PAr is non-monotonic. It is a consequence of the cooperative action of electron inelastic collisions of the first and second kinds with Na atoms and elastic collisions with Na and Ar atoms. The comparison of the obtained results for the L = 4R = 0.02 m case with those calculated for the infinite cylinder case with the same R value showed the good validity of the infinite cylinder approximation. As a result of our analysis of the quenching of the resonance levels and theoretical results from the literature, it has been established that the spatial non-homogeneity of the investigated photoplasma caused by this quenching does not exceed 20 % for the PNa≤0.1 torr and PAr/PNa=0 − 103. The obtained data can be used in studies of alkali-containing photoplasmas and to create photoelectric converters based on them.

Depth profile CF LIBS analysis of the wall deposited layer in the COMPASS tokamak after LiSn testing campaign

Plasma-facing materials in tokamak nuclear reactors are subject to intense heat and radiation. The design of liquid metal (LM) divertor walls has several advantages over the solid counterparts. It is important to understand the migration and re-deposition of LMs such as lithium (Li), lead (Pb) or even tin (Sn). This work presents CF LIBS depth profile analysis of the deposited layer on Ni–Cr based screws situated at different places in the COMPASS tokamak vessel during the Capillary Porous System (CPS) LM (LiSn) divertor testing campaign. The experiment was carried out at low Ar pressure (100 mbar) using ns Nd:YAG laser operating at 532 nm. The spectra were recorded using echelle spectrometer (M5000, Andor Tech.) equipped with an iCCD camera (iStar DH743, Andor Tech.). The quantification was based on observed C I, B I, Li I and (weak) Sn I lines, in addition to trace elements (Ca, Na, K) and main matrix elements (Cr, Ni, Fe). The evaluation of electron temperature and density was based on Cr I-II, Ni-II and Fe I-II lines. The LM based content is estimated to be Li (0.3-0.81 at.%) and Sn (0.1-0.23 at.%) with Li/Sn at.% ratio ranging from 3 to 3.5 (wt.% ratio of 0.17-0.20). In practise, the limit of detection of Sn by CF LIBS for this type of Cr-Ni-Fe based matrix is observed to be ∼0.1 at.%.

Comprehensive investigation of sputtering deposition pressure effects on a-InGaZnO Schottky diodes

The effects of Ar sputtering deposition pressure on the optical, structural, morphological, and electrical properties of amorphous InGaZnO thin films were investigated. The InGaZnO thin films, which have amorphous structures determined by grazing incidence x-ray diffraction, contained In, Ga, Zn, and O confirmed by secondary ion mass spectrometry method. Additionally, when the thicknesses of the deposited thin films are examined, it was seen that the profilometer measurement results of the crater formed by secondary ion mass spectrometer and scanning electron microscope measurement results are nearly similar, and it is approximately 100 nm. The surface roughness, obtained from Atomic Force Microscopy results, show that decreased up to a particular value with the increase of the working pressure, and then the surface roughness increased. The optical band gaps of the films were obtained in the range of 3.50 eV−3.58 eV via Tauc relation by using the Ultraviolet-Visible measurements carried out in the wavelength range of 200 nm−1100 nm. It was seen that the optical band gap was decreased with the increase in Ar pressure. The electrical properties of InGaZnO thin film-based Schottky diodes, such as the barrier height, ideality factor, saturation current, series resistance, and shunt resistance, have also been studied comprehensively. The electrical results showed that diode properties change with increasing deposition pressure.

Tuning microstructure and properties of MoNbTaWZr high entropy alloy films by adjusting the parameters in high power impulse magnetron sputtering

Within this study a series of MoNbTaWZr thin films were synthesized using high power impulse magnetron sputtering (HiPIMS) with varying the deposition parameters: duty cycle from 0.5 to 100 % (i.e. DC magnetron sputtering (DCMS)), Ar pressure from 0.5 to 3 Pa and pulse frequency from 25 to 200 Hz. The structure of the deposited films was analyzed by X-ray diffraction and scanning and transmission electron microscopy. In addition, the electrical resistivity and the residual stress of the films was determined. The influence of the deposition parameter variation on structure and properties of the MoNbTaWZr films is discussed on the established framework of film growth conditions achievable with HiPIMS and DCMS and how they can be influenced by adapting the deposition parameters. The performed work is intended to contribute to a comprehensive understanding about synthesis-structure-property relations for refractory high entropy alloy thin films while using MoNbTaWZr films as a model system.

Effect of Ar pressure on the wettability of copper droplet on graphite substrate by molecular dynamics simulation

Effect of Ar pressure on the wettability of copper droplet on graphite substrate by molecular dynamics simulation

Surface-disorder and cationic-site defect-induced ferromagnetism and correlated Raman vibrational modes in Sn0.9 In0.1O2 nanocrystalline thin-films

Exploration of magnetism in otherwise nonmagnetic wide-band oxides through defect-engineering has been become a new challenge to achieve the goal of room-temperature ferromagnetic semiconductor for potential applications in spintronics. In this backdrop, we report surface-disorder and cationic-site defect-induced FM in series of Sn0.9In0.1O2 nanocrystalline thin films prepared using pulsed laser deposition different Argon (Ar) pressure. With the increase of deposition pressure, surface morphology of Sn0.9In0.1O2 nanocrystalline thin-films changes as nanoclusters, nanofibres, nanoflakes and nanowires respectively, crystallite size decreases and surface disorder increases gradually. Raman, X-ray photoelectron and Photoluminescence spectroscopic analysis confirm the formation tin-vacancy (VSn) and associated combinational defects that significantly increase the ferromagnetic signal in In-doped SnO2 thin-films. The substitution of trivalent In3+ in Sn site also cause serious lattice distortion which transform the Raman inactive modes A2g and Eu modes into Raman active modes and thus appeared at 574 cm−1 and 354 cm−1 respectively. The nanowires of Sn0.9In0.1O2 are found to possess highest concentration of VSn defects and therefore it exhibits strongest ferromagnetic moment (MS) ∼ 11.1 emu/cm3 and highest Curie temperature (TC) ∼ 572 K. The gradual decrease in carrier concentration with the increasing deposition pressure suggests stabilization of hole-mediated VSn-induced room temperature FM in series of In-doped SnO2 nanocrystalline thin-films.

Tuning the morphology of sputter-deposited platinum catalyst: From compact layers to dispersed nanoparticles

A comprehensive study on adjusting the morphology of sputter-deposited platinum was performed. Platinum was deposited under various Ar pressure ranging from 0.3 to 3.2 Pa using a conventional magnetron system as well as at 57 Pa using a gas aggregation cluster source integrated into the magnetron sputtering system. The morphology and structure of deposited layers were characterized with a broad portfolio of characterization techniques such as scanning electron microscopy, transmission electron microscopy, grazing incidence small angle X-ray scattering and X-ray diffraction. The results revealed a continuous evolution of the Pt layer morphology from a thin-film-like layer of tightly packed Pt nanoparticles to a deposit composed of dispersed particles of 5-7 nm in size as the Ar pressure increased. The electrochemically active surface area of deposited Pt, as calculated from cyclic voltammograms, increased with deposition pressure from 11.7 m2·gPt−1 to 22.3 m2·gPt−1 and 24 m2·gPt−1 for Pt deposited at 0.3, 3.2 and 57 Pa, respectively. This increase in active sites was reflected in a significant improvement in the mass activity of platinum exemplary confirmed using a methanol electrooxidation reaction.

Effects of a modified argon glow plasma source on PET polymeric surface properties

A homemade plasma source with a Langmuir electrical probe was built in this work to create a plasma beam that could be utilized successfully in a range of uses. By modifying the operational parameters, including the discharging voltage, cathode–anode spacing and argon (Ar) pressure, a steady discharging medium was achieved. Additionally, a locally designed electrical probe was introduced into the discharging plasma to monitor the current–voltage (I–V) characteristics curve in order to assign plasma properties. The probe was moved to any intended destination in the plasma volume and had the following dimensions: 1 mm length and 0.5 mm diameter. The gas pressure and probe–cathode separation were modified to measure the plasma characteristics, including the electron density and electron temperature. It is found that as the pressure rises from 0.15 to 0.3 Torr, the electron temperature T e varies from 4.66 × 104 to 2.91 × 104 eV. When a poly(ethylene terephthalate) (PET) polymeric film is subjected to argon plasma beams, its surface wettability is altered. When the plasma period is increased from 0 to 8 min, the overall surface free energy rises from 32.2 to 67.7 mJ/m2. Additionally, the developed plasma source is highly efficient and tailored to satisfy the needs of applications such as polymeric surface modifications.