A physical vapor deposition process using anodic arc evaporation in combination with a hollow cathode arc discharge was applied to the evaporation of graphite for deposition of hydrogen-free carbon layers. The diamond-like carbon (DLC) films deposited on 100Cr6 steel substrates were investigated by nanoindentation, Raman spectrometry, FE-SEM, AFM and spectroscopic ellipsometry. The relationships between the process parameters and the coating properties are discussed. Coatings deposited without bias voltage at substrate temperatures <200 degrees C are very hard (61-75 GPa) with also very high Young's modulus (588-685 GPa). The evaluation of the Raman spectra indicated a high proportion of tetrahedral sp(3) bonds in the range of 70-88 %. Obviously, the vapor particle energies are high enough to achieve such high hardness values even without application of a bias voltage. The coatings proved to be completely droplet-free and have a very low surface roughness as confirmed by FE-SEM and AFM. The deposition rates in the range of 4-18 nm/s are exceptionally high for such tetrahedral amorphous carbon (ta-C) coatings, which is a good prerequisite for industrial applications. The ta-C layers with very high hardness and smooth surface are well suited as wear resistant layers.

Replacing conventional electrode materials is one of the most pressing challenges for next-generation lithium-ion batteries since state-of-the-art systems have almost reached their limitations for performance gains. For anodes, ambitious candidates include lithium and silicon because of their extremely high capacity. In this paper, a physical vapor deposition process for the preparation of pure metallic lithium layers and lithiated silicon layers in the layer thickness range of 1–20 µm is demonstrated. The lithium layers were deposited by thermal evaporation. Static coating rates up to 120 nm/s and dynamic deposition rates up to 1 µm·m/min were realized. Furthermore, the deposition of lithiated silicon alloy layers with various compositions was performed via the co-evaporation of lithium and silicon, where silicon was evaporated by an electron beam. The process was characterized regarding the deposition rate, heat loads, and effects of substrate pre-treatment. To achieve a porous microstructure, the layer morphology needed to be manipulated by adapting process parameters. Stripping experiments revealed high electrochemical activity of the lithium up to 85 %. The innovative approach carried out via vacuum processing showed capabilities for overcoming the current bottlenecks experienced with high-capacity anode materials in combination with the potential for upscaling to high throughput production.

With the anodic vacuum arc discharge as a method of physical vapor deposition (PVD) excellent properties of thin transparent conductive oxide films can be achieved, but the relations between the process parameters and the coating properties have been insufficiently described in the literature. This paper is intended to narrow this gap by investigations on indium tin oxide (ITO) thin films deposited on borosilicate glass sheets by sublimation of indium tin oxide (90:10) using an anodic vacuum arc. The arc discharge is based on a hot hollow cathode electron source and a special evaporator connected as anode. The concentration of the discharge onto the sublimating material is achieved by combining the magnetic fields of an axially symmetrical permanent magnet system and a solenoid coil. Coating rates of about 15 nm/s were achieved with an arc current of 60 A. Measurements with a planar Langmuir probe have shown that the vapor is highly ionized (about 95%). The discharge voltages are relatively low (< 60 V), so it can be assumed that the particle energies are correspondingly low. Substrate temperature (30-300 degrees C), oxygen gas flow (0-100 sccm) and gas pressure (0.04-0.4 Pa) were varied to study their influence on the thin film properties. Specific electrical conductivity, density and mobility of charge carriers, as well as optical properties were determined and compared with those of other PVD processes. Low specific electrical resistance of 1.8-2.0 x 10-4 omega cm was reached at a substrate temperature of 200-300 degrees C independently of the pressure. The mean optical transmission (in the spectral range between 400 nm and 1100 nm) of 100 nm thick ITO films deposited at a temperature of 200 degrees C and at an optimized oxygen flow was determined to 84%. The roughness of the layers determined by atomic force microscopy is significantly lower than typically for magnetron sputtered films. At a pressure of 0.04 Pa, the crystalline bixbyite phase can already be detected at a coating temperature of approx. 30 degrees C, whereby the layer growth begins with the formation of an amorphous structure and changes to the crystalline phase with increasing layer thickness. At a temperature above 100 degrees C and low coating pressure the layers are completely crystalline. At a higher pressure the transition from amorphous to crystalline phase is shifted towards higher temperature. For lower oxygen flows the crystallites exhibit mainly a preferred (211) orientation. For higher oxygen flows the texture of crystallites is changed and the intensity of (440) and (622) is increased. The formation of these special crystallographic textures can probably explain the very low roughness values of the ITO layers measured by atomic force microscopy. The investigations have shown how the film properties can be adjusted by the process parameters and that the ITO sublimation using an anodic vacuum arc is suited very well for plasma assisted ITO thin film deposition.

Porous thin films have various application fields, e.g., for energy conversion in fuel cells, energy storage in lithium ion batteries or supercapacitors as well for catalysis, filtration and sensing. We synthesized porous thin films by co-evaporating a low-vapor-pressure material (e.g., Si, Ni or C) together with zinc and depositing a compact layer of resulting composite. High-rate deposition process up to 100 nm/s was realized by electron beam physical vapor deposition (EB-PVD) of the materials from two graphite crucibles with a fast deflected electron beam in high vacuum. Immediately after deposition, the coated substrates were heated up in vacuum to a temperature above 500 degrees C and thereby zinc is removed selectively. Due to its higher vapor pressure against that of remaining component, zinc is expelled from the layer and vacancies are generated by so called vapor phase dealloying (VPD). We investigated the feasibility of VPD process for the elements silicon, nickel and carbon. The elemental composition and the morphology of the layers prior and after thermal annealing were analyzed by scanning electron microscopy, by energy-dispersive X-ray spectrometry and by X-ray diffraction.

Porous silicon thin films were fabricated by an innovative method using vacuum processing for the application as high capacity anode in lithium ion batteries. The deposition procedure comprises a co-evaporation of silicon and zinc, resulting in a deposition of a compound layer with deposition rates up to 100 nm/s and a subsequent thermal annealing. Due to its high vapor pressure, the zinc fraction is expelled and hence, a porous silicon matrix is formed. Herein, we introduce a novel and potentially scalable synthesis method for porous silicon films and show first analytical investigations concerning the layer morphology and the electrochemical properties. With the novel silicon anode excellent electrochemical performance, particularly high capacities of >= 3000 mAh/g, reasonable coulombic efficiencies of >= 90% in the initial cycle and comparably high cycle life > 150 cycles can be demonstrated, which reveals their great potential for battery anode applications.

In photovoltaics (PV) and microelectronics, there is an ongoing need for fabrication of silicon thin films with excellent material properties and with minimum production cost at the same time. To overcome fabrication gaps we present reached results for depositing silicon thin films by crucible-free electron beam physical vapor deposition (EB-PVD) and for plasma pretreatment of the substrates. The crucible-free EB-PVD process could be improved regarding critical aspects, e.g. occurrence of ingot cracks during heating up of monocrystalline Si evaporation material and spill out of the Si melt on the melting pool edges. Deposition rates above 500 nm/s, corresponding to 30 mu m/min, have been reached. Relating heat fluxes will be presented and discussed. By using a double ingot arrangement and superposing vapor from multiple sources the relative deviation of layer thickness could be reduced to < +/- 5% on a substrate width of 200 mm.

SummaryLithium‐Ion Batteries – Potential of vacuum thin film processes in productionIn modern societies, daily life would not be possible without lithium‐ion‐batteries. Their market share is expected to grow continuously throughout the next years. Nevertheless, from a technical point of view, there is still a large need for improvement and optimization of the cells and their production processes. Vacuum thin film processes can probably add a good share to this improvement. This article tries, without claiming to be exhaustive, to show the potential of vacuum processes in the field of lithium‐ion‐batteries, based on experience and examples projects Fraunhofer FEP worked on, pointing out possible starting points inside the battery cell. And by doing this, scalability to industrial scale processes is always kept in mind.

In modern societies, daily life would not be possible without lithium-ion-batteries. Their market share is expected to grow continuously throughout the next years. Nevertheless, from a technical point of view, there is still a large need for improvement and optimization of the cells and their production processes. Vacuum thin film processes can probably add a good share to this improvement. This article tries, without claiming to be exhaustive, to show the potential of vacuum processes in the field of lithium-ion-batteries, based on experience and examples projects Fraunhofer FEP worked on, pointing out possible starting points inside the battery cell. And by doing this, scalability to industrial scale processes is always kept in mind.

Some applications in energy technology will require large-area and dense coatings of yttria-stabilized zirconia (YSZ) while high coating rate is demanded for economic reasons. A combination process of co-evaporation of yttrium and zirconium by EB-PVD from a dual crucible, reactive processing procedure of introducing oxygen, and a spotless arc burning between zirconium as cathode and yttrium as anode were investigated experimentally. The YSZ layers were deposited at relatively high static coating rates (20 to 80 nm s(-1)) in comparison to other PVD processes. The cubic crystal structure that was identified by means of XRD corresponds to the YSZ phase with the highest ionic conductivity and is therefore especially well-suited for use as a solid-state electrolyte. Pores were evidenced in the microstructure of the layers deposited at a coating rate of >50 nm s(-1). Nevertheless, very dense YSZ layers could be obtained at a coating rate of 30 nm s(-1) and a spotless arc current of 300 A. Specific leakage rates of YSZ layers on porous Ni/NiO-YSZ anode substrates measured using air are in the region of 1 Pa m s(-1). The investigations have shown that the intense plasma created with a spotless arc has a considerable influence on growth and microstructure of YSZ layers, even at high coating rates. (C) 2017 Elsevier B.V. All rights reserved.

Results of investigations on thin films of titanium oxide are presented in which the layers were deposited at a very high deposition rate of approximately 50–100nm/s. The high-performance coating process is based upon electron beam evaporation, a dual crucible, and a spotless arc that burns in the metal vapor and reactive gas between the evaporating titanium electrodes that are heated by the electron beam. Electron beam power, arc current and oxygen flow rate were varied and the resulting coatings investigated with regard to their composition, optical properties, and microstructure. Even at such high deposition rates, transparent and dense layers with a high refractive index (2.4) could be produced. Amorphous TiO2 coatings were obtained at a substrate temperature below 150°C while crystalline layers of the anatase form could be deposited at a substrate temperature in the range of 200 to 300°C. The data regarding the chemical composition of the titanium oxide layers are compared with a mathematical model of reactive vapor deposition. An estimate based on the model shows that the incorporation coefficient of oxygen, which gives its deposit probability in the coating, is approximately 0.25 for stoichiometric TiO2 layers. Possible applications of the PVD process presented are foreseen for large-area optical coating systems and large-scale application of photo-induced effects.

It is essential that corrosion monitoring of indoor atmospheres should be highly sensitive, especially, when corrosion rates corresponding to the lowest standard corrosivity categories are supposed to be identified within one or a few days. The electrical resistance technique in combination with high-sensitivity electrical resistance sensors enabled detection of a corrosion loss on an atomic scale. Case studies have demonstrated the sensors’ ability to timely inform the users about changes in the atmosphere quality. In confrontation with quartz crystal microbalance technique, resistometric sensors provided better explainable data.

It is essential that corrosion monitoring of indoor atmospheres be highly sensitive, especially when corrosion rates corresponding to the lowest standard corrosivity categories are supposed to be identified within one or a few days. The electrical resistance (ER) technique in combination with high sensitivity ER sensors enabled detection of corrosion loss on an atomic scale. The magnetron sputtering method was used to produce sensors equipped with 50 to 800 nm metallic track. The set of developed sensors represent a wide range of materials, e.g. copper, silver, iron, lead and bronze. Laboratory experiments have proven that copper and silver sensors respond to changes in relative humidity and temperature within minutes. Bronze and copper sensors are able to detect changes in concentrations of volatile organic acids, which are common pollutants of indoor atmospheres in museums.

A system for continuous monitoring of atmospheric corrosivity has been developed. An electronic unit measures and records changes in the electrical resistance of a thin metal track applied on an insulating substrate. If the metal corrodes, the effective cross sectional area of the track decreases and the electrical resistance increases. Sensors made of silver, copper, iron/steel, zinc, lead, tin, aluminium, bronze, and brass at thicknesses from 50 nm to 250 mu m were tailored for environments with different corrosivities. The developed technology proved capable of providing high sensitivity, allowing for real-time corrosion monitoring even in low-corrosive indoor cultural heritage facilities. Laboratory tests showed good reproducibility with the standard deviation of parallel measurements at less than +/- 20% for metals which corrode uniformly in the tested environments. Several examples selected from a broad testing programme in partner museums, libraries, and other institutions show successful applications of the logger system for characterization of air quality control in indoor locations, during transport and in temporary exhibitions; assessment of new buildings and storage facilities; and fundamental studies of optimal conservation and storage procedures. A first outline of a classification system for lead, which is particularly sensitive to the presence of carboxylic acids, is given. The technique has a large potential as an independent method for monitoring air quality in facilities displaying and storing valuable objects of cultural heritage.

For deposition of thin oxide coatings there are a lot of qualified PVD processes today. If high productivity or large-area coating is necessary for economic reasons processes with high deposition rate are reasonable. Using electron beam (EB) evaporation all inorganic materials can be evaporated with high rates. Microstructure of coatings deposited by EB-evaporation depends on substrate temperature during layer growth and melting temperature of coating material. Particularly in case of high melting materials columnar and porous microstructure is obtained. For large area coating several plasma sources have been developed in order to enhance energy of condensing particles and to get denser layer microstructure.Spotless arc Activated Deposition (SAD) combines electron beam high-rate evaporation using axial gun and a spotless arc discharge burning in metal vapor on hot evaporating cathode [2]. The SAD process is suitable for evaporation of high-melting metals like titanium, zirconium or tantalum providing high deposition rate up to 2000 nm/s. Moreover plasma-activation enables reactive mode of operation and deposition of oxides, nitrides or other compounds with a high rate in the range of 20 to 100 nm/s. A Spotless arc is an arc discharge burning in metal vapor which is obtained if the cathode temperature is high enough to enable high thermionic electron emission current density. Spotless mode results in relatively low cathodic arc current density and droplets known from arc evaporators with cold cathode are completely avoided [3]. Nevertheless high DC arc current up to 2000 A is possible.Recent work has shown that SAD process is well suited for deposition of titanium dioxide coatings based on evaporation of titanium and reactive processing in oxygen atmosphere [4]. TiO2 layers were deposited at very high deposition rates between 40 and 70 nm/s. Depending on process conditions amorphous coatings or crystalline phases were obtained. Coatings consisting of anatase phase show very good properties concerning photoinduced superhydrophilicity and photocatalysis. Transparent layers with high refractive indexes in the range of 2.30 and 2.58 could be reached.

A technique for continuous monitoring of atmospheric corrosivity was developed. An electronic unit measures and records changes in the electrical resistance of a thin metal track applied on an insu ...

Possibilities of using of high voltage glow discharge electron guns for deposition of chemically complex coatings in the controlled gas medium with the arc ionizing of vapors flow is considered. The structure of obtained coatings is investigated. Keywords - Electron beam evaporation, High Voltage Glow Discharge (HVGD), composite coaings, nanostructurized coatings.