Suchergebnisse

Magnetron sputter deposition of TiBx thin films from a TiB2 target typically results in highly overstoichiometric films due to differences in sputtered-atom ejection angles and gas-phase scattering during transport to the substrate. This study investigates the effects of the magnetron magnetic field strength at the substrate position and the Ar sputtering pressure on the resulting film composition and crystalline quality. It is shown that the B/Ti atomic ratio can be reduced from 2.7 to 2.1 by increasing the Ar pressure from 5 mTorr to 20 mTorr, a trend consistent with previous work. Despite the use of a relatively high Ar pressure, a change to a stronger outer magnetic pole leads to, dense TiB2.1 films of high crystal quality, as shown by X-ray diffraction, scanning transmission electron microscopy, and specific resistivity of 32 mu Omega cm. For epitaxial films deposited at 900 degrees C on Al2O3(001), a TiB2[110]//Al2O3[100] orientational relationship were obtained. ; Funding Agencies|Knut and Alice Wallenberg (KAW) FoundationKnut & Alice Wallenberg Foundation [KAW 2015.0043]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Link_oping University [2009 00971]; VR-RFI (Vetenskapsradet) [821-2012-5144]; Swedish Foundation for Strategic ResearchSwedish Foundation for Strategic Research [SSF, RIF14-0053]

Financial support provided by Scientific Research Project for Students and Young Researchers Nr. SJZ/2017/4 realised at the Institute of Solid State Physics, University of Latvia is greatly acknowledged. ; Reactive high power impulse magnetron sputtering (R-HiPIMS) has been demonstrated as a promising technique for the ZnO:Al (AZO) thin film deposition at low temperature with improved electrical properties compared to the reactive direct current magnetron sputtering (R-dcMS). However, there are not enough studies about the HiPIMS process using Zn/Al target itself. Additionally, AZO films have not been deposited with the pulse duration times long enough to allow the discharge to develop into the self-sputtering mode. C-V-t characteristics and the time average plasma optical emission spectra were studied as a function of different sputtering parameters, such as frequency, average power, pulse duration time, and oxygen flow rate. AZO films were deposited on glass substrates without intentional heating by R-HiPIMS using 500 μs long pulses. Structural, electrical and optical properties of the AZO films were studied as a function of peak current. Obtained peak power densities are relatively low compared to other metals due to the strong argon gas rarefaction, however, it is possible to increase the peak power density above 0.5 kW/cm2 by increasing the time between pulses or the average power to reach the HiPIMS regime. If the pulse duration time is 500 μs, the sustained self-sputtering discharge can be observed when the peak power density is above 0.3 kW/cm2. The peak current is sensitive to the oxygen content in the sputtering atmosphere so that it can be used as a control parameter for the reactive sputtering. The lowest obtained resistivity of the AZO films is 1.0 × 10−3 Ωcm with the transmittance around 70% in the visible light range. From the XRD measurements, there is the indication of existing zincblende structural phase in the R-HiPIMS deposited AZO films using high oxygen partial pressure. ; University of Latvia Nr. SJZ/2017/4; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union's Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART²

In the present work, the effect of the cylindrical configurations of the sputtering device electrodes on the plasma parameters (Debye length, electron temperature, electron density, plasma frequency) is studied. Also, the effect of the argon gas pressure on the discharge properties is examined with gas pressures of (0.08, 0.2, 0.4 and 0.6) Torr. The properties of the plasma are diagnosed by optical emission spectrometry. The spectroscopic method is adopted for examining the atomic spectra of argon emission. The electron temperature is determined by the Boltzmann method. While, the Stark-widening method was employed for calculating the electron number density. The voltage against current curves of the cylindrical sprayer discharges shows the voltage to be nearly constant with slight increase in current. An increase in pressure causes the cathode cascades to compress and the negative glow to become thinner and more luminous. Plasma properties such as electron temperature and Debye length decrease with increasing pressure, while electron number density and plasma frequency increase.

Glancing angle deposition (GLAD) of AlN nanostructures was performed at room temperature by reactive magnetron sputtering in a mixed gas atmosphere of Ar and N-2. The growth behavior of nanostructures shows strong dependence on the total working pressure and angle of incoming flux. In GLAD configuration, the morphology changed from coalesced, vertical nanocolumns with faceted terminations to highly inclined, fan-like, layered nanostructures (up to 38 degrees); while column lengths decreased from around 1743 to 1068 nm with decreasing pressure from 10 to 1.5 mTorr, respectively. This indicates a change in the dominant growth mechanism from ambient flux dependent deposition to directional ballistic shadowing deposition with decreasing working pressures, which is associated with the change of energy and incident angle of incoming reactive species. These results were corroborated using simulation of metal transport (SiMTra) simulations performed at similar working pressures using Ar and N separately, which showed the average particle energy and average angle of incidence decreased while the total average scattering angle of the metal flux arriving at substrate increased with increasing working pressures. Observing the crystalline orientation of GLAD deposited wurtzite AlN nanocolumns using X-ray diffraction (XRD), pole-figure measurements revealedc-axis growth towards the direction of incoming flux and a transition from fiber-like to biaxial texture took place with increasing working pressures. Under normal deposition conditions, AlN layer morphology changed from {0001} to {10 (1) over bar1} with increasing working pressure because of kinetic energy-driven growth. ; Funding Agencies|VetenskapsradetSwedish Research Council [2018-04198]; Energimyndigheten [46658-1]; Stiftelsen Olle Engkvist ByggmastareSwedish Research Council [197-0210]; Linkoping University Library; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [SFO-Mat-LiU 2009-00971]

This paper defines a method for sputtering high strength, extremely conductive silver mirrors on glass substrates at temperatures ranging from 20o to 22o C. The silver coated layer thicknesses in this work ranges from 7.5 to 16.1 nm using sputtering time from 10 to 30 min at power 25 W, 13.7 to 29.2 nm for time 10 to 30 min at 50 W, 15.7 to 26.4 nm for time 10 to 30 min at 75 W and 13.8 to 31.1 nm for time 10 to 30 min at 100 W. The optimum values of pressure and electrode gape for plasma sputtering system are 0.1 mbar and 5 cm respectively. The effect of DC sputtering power, sputtering duration or (sputtering time), and thickness on optical properties was investigated using an ultraviolet-visible spectrophotometer. The ultraviolet absorption of all coated layers was high, while the visible absorption was low. The transmittance is decrease with increase sputtering time and sputtering power. Highest values of reflection in visible region at 100 W and 20, 25 and 30 min are 46% to 97%. High value of band gap at 100 and 30 min while lower value at 25 W and 10 min.

In this work, the electrical properties and optimum conditions of the plasma sputtering system have been studied. The electrical properties such as Paschen's curve, current-voltage, current pressure relations, the strength of magnetic field as a function of inter-electrode distance, the influence of gas working pressure and argon-oxygen ratio on the electrical characterization were studied to determine the basic optimum condition of the system operation. the discharge current as a function of discharge voltage showed high discharge current at 2.5 cm. These parameters represent the basic conditions to operate any plasma sputtering system which are the right behavior to build up and design the discharge an electrode. The ideal conditions of these homemade systems were qualified to prepare the various nanostructure thin films. The two electrodes were made of copper because of its good conductivity, and to avoid the power dissipation inside discharge chamber.

We deposit CSx thin solid films by reactive direct current magnetron sputtering of a C target in an argon plasma, using carbon disulfide (CS2) as a precursor to film growth. We investigate the influence of the partial pressure of the CS2 vapor introduced into the plasma on the composition, the chemical bonding structure, the structural, and the mechanical properties as determined by x-ray photoelectron spectroscopy (XPS), Raman spectroscopy, scanning electron microscopy (SEM), and nanoindentation for films deposited at 150 and 300 degrees C. The Raman and the XPS results indicate that S atoms are incorporated in mostly sp(2) bonded C network. These results agree with previous ab-initio theoretical findings obtained by modeling of the CSx compound by the Synthetic Growth Concept. The microstructure of the films as well as the results of their Raman characterization and the nano mechanical testing results all point out that with the increasing S content some spa bonding is admixed in the predominantly sp(2) bonded CSx network, leading to typical amorphous structure with short and interlocked graphene-like planes for S contents between 2% and 8%. We conclude that CSx thin solid films deposited by using CS2 as a precursor would be CSx films deposited at low temperature of similar to 150 degrees C and with an S content in the region of 6 at.% may be interesting candidates for applications as hard/elastic protective coatings. ; Funding Agencies|Swedish Government Strategic Research Area in Materials Science on Advanced Functional Materials at Linkoping University [SFO-Mat-LiU 2009-00971]; Swedish Research Council (VR) through FLAG-ERA JTC 2015 project GRIFONESwedish Research Council [VR 2015-06816, VR 2017-04071]; Aforsk grant [18-266]; VRSwedish Research Council [VR 2016-05362]; Knut and Alice Wallenberg (KAW) FoundationKnut & Alice Wallenberg Foundation [KAW 2015.0043]

This work is an experimental study conducted to study the effects of iron oxide dust particles (Fe2O3) on the characteristics of DC discharge plasma in argon gas under vacuum. Electron temperature ( ) and electron density (ne) were calculated by Boltzmann plots and Stark broadening, respectively. The results show that both the electron density and plasma frequency ( ) increased with the operating pressure. While, and Debye length ( ) decreased with pressure. The glow discharge is more stable with the Fe2O3-dust particles; all dust plasma parameters have lower values than those of the dust-free plasma.

CrB x thin films with 1.90 < x < 2.08 have been deposited by direct-current magnetron sputtering (DCMS) from a stoichiometric CrB 2 target at 5 and 20 mTorr (0.67 and 2.67 Pa) Ar pressure onto sapphire (0 0 01) substrates. All films, irrespective of deposition conditions, exhibit a (0 0 01) texture. Attesting to the achievement of close-to-stoichiometric composition, epitaxial film growth is observed at 900 ?C, while film growth at 500 ?C yields (0001) fiber texture. Film composition does not depend on substrate temperature but exhibits slightly reduced B content with increasing pressure for samples deposited at 900 ?C. Excess B in the overstoichiometric epitaxial CrB 2.08 films segregates to form B-rich inclusions. Understoichiometry in CrB 1.90 films is accommodated by Cr-rich stacking faults on { 1 1? 00 } prismatic planes. ? 2021 The Author(s). Published by Elsevier Ltd on behalf of Acta Materialia Inc. This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ ) ; Funding Agencies|Swedish Foundation for Strategic Research (SSF)Swedish Foundation for Strategic Research [EM16-0004, RIF 14-0074]; Knut and Alice Wallenberg (KAW) FoundationKnut & Alice Wallenberg Foundation [KAW 2015.0043]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [200900971]; KAW

A theoretical and experimental study on the growth and properties of a ternary carbon-based material, CSxFy, synthesized from SF6 and C as primary precursors is reported. The synthetic growth concept was applied to model the possible species resulting from the fragmentation of SF6 molecules and the recombination of S-F fragments with atomic C. The possible species were further evaluated for their contribution to the film growth. Corresponding solid CSxFy thin films were deposited by reactive direct current magnetron sputtering from a C target in a mixed Ar/SF6 discharge with different SF6 partial pressures (P-SF6). Properties of the films were determined by x-ray photoelectron spectroscopy, x-ray reflectivity, and nanoindentation. A reduced mass density in the CSxFy films is predicted due to incorporation of precursor species with a more pronounced steric effect, which also agrees with the low density values observed for the films. Increased P-SF6 leads to decreasing deposition rate and increasing density, as explained by enhanced fluorination and etching on the deposited surface by a larger concentration of F/F-2 species during the growth, as supported by an increment of the F relative content in the films. Mechanical properties indicating superelasticity were obtained from the film with lowest F content, implying a fullerene-like structure in CSxFy compounds. ; Funding Agencies|Swedish Foundation for Strategic Research (SSF) Synergy Grant on Functional Carbides and Advanced Surface Engineering (FUNCASE) [RMA11-0029]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009-00971]

Two series of Nb–Si–C thin films of different composition have been deposited using DC magnetron sputtering. In the first series the carbon content was kept at about 55 at.% while the Si/Nb ratio was varied and in the second series the C/Nb ratio was varied instead while the Si content was kept at about 45 at.%. The microstructure is strongly dependent on Si content and Nb–Si–C films containing more than 25 at.% Si exhibit an amorphous structure as determined by X-ray diffraction. Transmission electron microscopy, however, induces crystallisation during analysis, thus obstructing a more detailed analysis of the amorphous structure. X-ray photo-electron spectroscopy suggests that the amorphous films consist of a mixture of chemical bonds such as Nb–Si, Nb–C, and Si–C. The addition of Si results in a hardness decrease from 22 GPa for the binary Nb–C film to 18 – 19 GPa for the Si-containing films, while film resistivity increases from 211 μΩcm to 3215 μΩcm. Comparison with recently published results on DC magnetron sputtered Zr–Si–C films, deposited in the same system using the same Ar-plasma pressure, bias, and a slightly lower substrate temperature (300 °C instead of 350 °C), shows that hardness is primarily dependent on the amount of Si–C bonds rather than type of transition metal. The reduced elastic modulus on the other hand shows a dependency on the type of transition metal for the films. These trends for the mechanical properties suggest that high wear resistant (high H/E and H3/E2 ratio) Me–Si–C films can be achieved by appropriate choice of film composition and transition metal. ; Funding Agencies|Vinnova (Swedish Governmental Agency for Innovation Systems) through the VINN Excellence Centre FunMat||Swedish Research Council (VR)||

The lower deposition rate for high power impulse magnetron sputtering (HiPIMS) compared with direct current magnetron sputtering for the same average power is often reported as a drawback. The often invoked reason is back-attraction of ionized sputtered material to the target due to a substantial negative potential profile, sometimes called an extended presheath, from the location of ionization toward the cathode. Recent studies in HiPIMS devices, using floating-emitting and swept-Langmuir probes, show that such extended potential profiles do exist, and that the electric fields E-z directed toward the target can be strong enough to seriously reduce ion transport to the substrate. However, they also show that the potential drops involved can vary by up to an order of magnitude from case to case. There is a clear need to understand the underlying mechanisms and identify the key discharge variables that can be used for minimizing the back-attraction. We here present a combined theoretical and experimental analysis of the problem of electric fields E-z in the ionization region part of HiPIMS discharges, and their effect on the transport of ionized sputtered material. In particular, we have investigated the possibility of a sweet spot in parameter space in which the back-attraction of ionized sputtered material is low. It is concluded that a sweet spot might possibly exist for some carefully optimized discharges, but probably in a rather narrow window of parameters. As a measure of how far a discharge is from such a window, a Townsend product Pi(Townsend) is proposed. A parametric analysis of Pi(Townsend) shows that the search for a sweet spot is complicated by the fact that contradictory demands appear for several of the externally controllable parameters such as high/low working gas pressure, short/long pulse length, high/low pulse power and high/low magnetic field strength. ; Funding Agencies|Swedish Research Council||Swedish Foundation for Strategic Research||European Collaboration in Science and Technology (COST Action)|MP0804|ANR HiPPoPP (French Government Research Agency)||Romanian ministry of Education, Research, Youth and Sport|IDEI 540/2009|

We report x-ray photoelectron spectroscopy (XPS) analysis of native Ti target surface chemistry during magnetron sputtering in an Ar/N-2 atmosphere. To avoid air exposure, the target is capped immediately after sputtering with a few-nm-thick Al overlayers; hence, information about the chemical state of target elements as a function of N-2 partial pressure p(N2) is preserved. Contrary to previous reports, which assume stoichiometric TiN formation, we present direct evidence, based on core-level XPS spectra and TRIDYN simulations, that the target surface is covered by TiNx with x varying in a wide range, from 0.27 to 1.18, depending on p(N2). This has far-reaching consequences both for modelling of the reactive sputtering process and for everyday thin film growth where detailed knowledge of the target state is crucial. Published by AIP Publishing. ; Funding Agencies|German Research Foundation (DFG) [SFB-TR 87]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant) [SFO Mat LiU 2009 00971]; Aforsk Foundation [16-359]; Carl Tryggers Stiftelse [CTS 15:219, CTS 14:431]

A broad interest has been showed recently on the study of nanostructuring of thin films and surfaces obtained by low‐energy He plasma treatments and He incorporation via magnetron sputtering. In this paper spatially resolved electron energy‐loss spectroscopy (EELS) in a scanning transmission electron microscope (STEM) is used to locate and characterize the He state in nanoporous amorphous silicon coatings deposited by magnetron sputtering. A dedicated MATLAB program was developed to quantify the helium density inside individual pores based on the energy position shift or peak intensity of the He K‐edge. A good agreement was observed between the high density (~35‐60 at/nm3) and pressure (0.3‐1.0 GPa) values obtained in nanoscale analysis and the values derived from macroscopic measurements (the composition obtained by proton backscattering spectroscopy coupled to the macroscopic porosity estimated from ellipsometry). This work provides new insights into these novel porous coatings, providing evidence of highdensity He located inside the pores and validating the methodology applied here to characterize the formation of pores filled with the helium process gas during deposition. A similar stabilization of condensed He bubbles has been previously demonstrated by high‐energy He ion implantation in metals and is newly demonstrated here using a widely employed methodology, magnetron sputtering, for achieving coatings with a high density of homogeneously distributed pores and He storage capacities as high as 21 at%. ; European Union CT‐REGPOT‐2011‐1‐285895 ; Consejo Superior de Investigaciones Científicas PIE 201060E102, PIE 201460E018 ; Ministerio de Economía y Competitividad CSD2008–00023, CTQ2012‐32519 ; Junta de Andalucía TEP217, PE2012‐TEP862