Abscheidung optisch,elektrisch und akustisch wirksamer Schichten mit dem Doppel‐Ring‐Magnetron

Numerous applications in optics, electronics and sensor technology require thin dielectric films. Conventionally they are deposited by evaporation, activated evaporation, rf‐sputtering or CVD‐techniques. This paper describes the deposition of such films using reactive Pulse Magnetron Sputtering. This technology not only enables a tenfold deposition rate compared to the conventional techniques but also offers new possibilities for influencing film growth. For example it is possible to alter film composition during deposition and hence to deposit complete optical systems without interruption of the plasma process. Furthermore the energetic bombardment of the growing film can be controlled in a wide range by the pulse mode and the pulse parameters. This can be used to either deposit very dense films by strong energetic bombardment or to deposit films at low thermal load onto temperature sensitive substrates. Examples of film deposition for laser optics, electrical insulation applications and surface acoustic wave devices show how these new technological possibilities advantageously can be used for creating innovative layer systems. Film deposition is carried out in stationary mode using a Double Ring Magnetron. This type of magnetron ensures film thickness uniformity better than ± 1 % on 8” substrates by the superposition of the thickness distributions of two concentric discharges.     

Gepulste Hochleistungs‐Magnetron‐Plasmen (HPPMS)

Control of High Power Pulsed Magnetron Plasmas (HPPMS) by Monitoring Current‐Voltage Characteristics High Power Pulsed Magnetron Sputtering (HPPMS) plasmas are perfectly suited for the synthesis of ceramic coatings with superior properties. This excellent performance is induced by the very peculiar energetic particle flux reaching the substrate to be coated. The ion energy distribution originates from the formation of localized ionization zones which can be imaged by fast cameras. In commercial HPPMS reactors, however, only much simpler methods such as current voltage characteristics (VI curves) are accessible. By a proper interpretation of those VI curves, it is possible to identify the favorable operation mode of an HPPMS plasma. The VI curves vary with target material, but they are sensitive to the occurrence of localized ionization zones, which represent the optimum for the operation parameter window of HPPMS plasmas.     

Dünne ITO‐Schichten als leitfähige,transparente Elektroden. Thin films of ITO as conductive,transparent electrodes

This article deals with materials science aspects of In₂O₃:Sn (“ITO”) coatings and with the process technology of variants of sputtering used to obtain thin films with properties desired for specific applications. As an example, antistatic and antireflective coatings of monitor tubes are presented. The influence of sputter parameters such as substrate temperature, plasma excitation mode, sputter pressure and oxygen partial pressure on the quality of the films is discussed. It is shown how application‐oriented basic research helps to obtain recipes for materials design. Two basic aspects are discussed in more detail: the influence of an oxygen surplus in the films on microstructure and electrical properties and the correlation of electrical and optical parameters of the films.     

Influence of the target composition on reactively sputtered titanium oxide films

Titanium dioxide thin films have many interesting properties and are used in various applications. High refractive index of titania makes it attractive for the glass coating industry, where it is used in low-emissivity and antireflective coatings. Magnetron sputtering is the most common deposition technique for large area coatings and a high deposition rate is therefore of obvious interest. It has been shown previously that high rate can be achieved using substoichiometric targets. This work deals with reactive magnetron sputtering of titanium oxide films from TiO_x targets with different oxygen contents.The deposition rate and hysteresis behaviour are disclosed. Films were prepared at various oxygen flows and all films were deposited onto glass and silicon substrates with no external heating. The elemental compositions and structures of deposited films were evaluated by means of X-ray photoelectron spectroscopy, elastic recoil detection analysis and X-ray diffraction. All deposited films were X-ray amorphous. No significant effect of the target composition on the optical properties of coatings was observed. However, the residual atmosphere is shown to contribute to the oxidation of growing films.     

Reaktives Magnetronsputtern von Dünnschichtsolarzellen

Reactive Magnetron Sputtering of Thin Film Solar Cells We show that reactive magnetron sputtering is well suited to deposit CuInS₂‐thin film absorber layers of high electronic quality. Using metallic targets and substrate temperatures below 500 °C, compact films with grain sizes in the micrometer range can be obtained. The structural and electronic properties of these layers are comparable to CuInS₂ thin films prepared by a 2‐step sulfurization process, which is being commercialized at present. In particular, the reactively sputtered films show minority carrier diffusion lengths larger than the layer thickness (≈ 2μm). This results in solar cells with conversion efficiences larger than 10 %, comparable to the best conversion efficiencies for CuInS₂‐solar cells obtained from other deposition processes. These results are promising for the potential application of magnetron sputtering as a large area deposition process for absorber layers in thin film solar cells.     

Photopatterning of Cross‐Linkable Epoxide‐Functionalized Block Copolymers and Dual‐Tone Nanostructure Development for Fabrication Across the Nano‐ and Microscales

The self‐assembly of block copolymers in thin films provides an attractive approach to patterning 5–100 nm structures. Cross‐linking and photopatterning of the self‐assembled block copolymer morphologies provide further opportunities to structure such materials for lithographic applications, and to also enhance the thermal, chemical, or mechanical stability of such nanostructures to achieve robust templates for subsequent fabrication processes. Here, model lamellar‐forming diblock copolymers of polystyrene and poly(methyl methacrylate) with an epoxide functionality are synthesized by atom transfer radical polymerization. We demonstrate that self‐assembly and cross‐linking of the reactive block copolymer materials in thin films can be decoupled into distinct, controlled process steps using solvent annealing and thermal treatment/ultraviolet exposure, respectively. Conventional optical lithography approaches can also be applied to the cross‐linkable block copolymer materials in thin films and enable simultaneous structure formation across scales—micrometer scale patterns achieved by photolithography and nanostructures via self‐assembly of the block copolymer. Such materials and processes are thus shown to be capable of self‐assembling distinct block copolymers (e.g., lamellae of significantly different periodicity) in adjacent regions of a continuous thin film.     

Optical characterization of transparent nickel oxide films deposited by DC current reactive sputtering

In this paper, we characterize high transparency p-type semiconducting NiO thin films deposited by Direct Current Reactive Magnetron Sputtering from a pure Ni target in a mixture of oxygen and argon gases on Corning glass/SnO₂:F substrates at different oxygen contents ranging from 0% at 30%. The influence of the O₂/Ar ratio and thickness on transmittance has been examined using ultraviolet-visible spectroscopy. The results show that whatever the oxygen proportion into the discharge, the nickel oxide films exhibit a polycrystalline structure. At low oxygen content, the preferential orientation is (111), for stoichiometric films the XRD diagram is powder-like whereas the preferential orientation is (200) for higher oxygen content. For low and high oxygen content, the transmittance is low. Thanks to plasma method and its ability to tune the oxygen content in the discharge and therefore the film composition, we have been able to explore carefully the intermediate zone and obtain transparent films. The optical absorption coefficient α has been calculated from the transmittance and the variation of (αhν)² versus the photon energy (hν) for nickel oxide is presented. The optical band gap energy has been evaluated and varies from 3.2 to 3.8 eV.     

Effect of UV‐Radiation on the Packaging‐Related Properties of Whey Protein Isolate Based Films and Coatings

The high oxygen barrier properties of whey protein based films and coatings means these materials are of great interest to the food and packaging industry. However, these materials have poor mechanical properties such as the tensile strength, Young's modulus and elongation at break. Up until now, the influence of ultraviolet (UV) radiation on whey protein films has not been reported in the literature. This study thus investigates the influence of UV‐radiation on the properties of whey protein based films. UV‐irradiated films showed increased tensile strength and a yellowing that was dependent on the radiation time. After irradiation, the films showed no significant change in the barrier properties, Young's modulus or elongation at break. In addition, a protein solubility study was undertaken to characterize and quantify changes in structure‐property relationships. The significant decrease in protein solubility in buffer systems which break disulfide and non‐covalent bonds indicates that additional molecular interactions arise with increasing radiation dose. This study provides new data for researchers and material developers to tailor the characteristics of whey protein based films according to their intended application and processing. Copyright © 2015 John Wiley & Sons, Ltd.     

Advanced key technologies for magnetron sputtering and PECVD of inorganic and hybrid transparent coatings

Besides classical multilayer systems with alternating low and high refractive indices, reactive pulse magnetron sputtering processes offer various possibilities of depositing gradient films with continuously varying refractive index. Using nanoscale film growth control it is possible to achieve optical filter systems with a defined dependency of refractive index on film thickness, e.g. by sputtering a silicon target in a time variant mixture of oxygen and nitrogen. Also reactive co-sputtering of different target materials such as silicon and tantalum in oxygen is suitable as well. Rugate filters made from SiO_xN_y or Si_xTa_yO_z gradient refractive index profiles find their application in spectroscopy, laser optics and solar concentrator systems.Furthermore polymer substrates are increasingly relevant for the application of optical coatings due to their mechanical and economical advantages. Magnetron PECVD (magPECVD) using HMDSO as precursor allows to deposit carbon containing films with polymer-like properties. Results show the suitability of these coatings as hard coatings or matching layers. Multifunctional coatings with antireflective and scratch-resistant properties were deposited on polymer substrates using a combined magPECVD and sputter deposition process.     

High‐Resolution Spin‐on‐Patterning of Perovskite Thin Films for a Multiplexed Image Sensor Array

Inorganic–organic hybrid perovskite thin films have attracted significant attention as an alternative to silicon in photon‐absorbing devices mainly because of their superb optoelectronic properties. However, high‐definition patterning of perovskite thin films, which is important for fabrication of the image sensor array, is hardly accomplished owing to their extreme instability in general photolithographic solvents. Here, a novel patterning process for perovskite thin films is described: the high‐resolution spin‐on‐patterning (SoP) process. This fast and facile process is compatible with a variety of spin‐coated perovskite materials and perovskite deposition techniques. The SoP process is successfully applied to develop a high‐performance, ultrathin, and deformable perovskite‐on‐silicon multiplexed image sensor array, paving the road toward next‐generation image sensor arrays.     

Magnetron sputter deposition of (SiC)<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>(AlN)<Subscript>x</Subscript> solid solution films

Magnetron sputtering of polycrystalline SiC-AlN targets was used to obtain films of (SiC)_{1− x} (AlN)_x solid solutions on silicon carbide (6H-SiC) substrates heated to a temperature in the range T = 500–1200°C. The deposits were characterized with respect to structure, composition, and optical absorption. It is demonstrated that the films obtained on 6H-SiC substrates at T ≥ 1000°C possess a single crystal structure. The compositions of (SiC)_1−x (AlN)_x films are close to those of the corresponding SiC-AlN targets.     

Domain studies of CoCr with perpendicular anisotropy

R.F. Magnetron sputtered CoCr films (79/21 at%) with various thicknesses are magnetically characterized. The domain structure is observed by digitally enhanced Kerr microscopy and depends on the Hc/Hk values of the samples. For low and high coercivity films a comparison is made between the measured VSM hysteresis, domain period and a theoretical domain model. The domain shape is a function of the magnetic history of the sample and the bending created by the deposition process.     

Verformungsverhalten nanostrukturierter HPPMS‐Hartstoffschichten

Elastic‐Plastic Deformation Behavior of Nanostructured HPPMS Hard Coatings Nitride hard coatings deposited via HPPMS (High Power Pulsed Magnetron Sputtering) or HiPIMS (High Power Impulse Magnetron Sputtering) are widely used in tribological applications due to their promising wear and corrosion resistance. During the application, the coated tools or components may be exposed to significant mechanical loads. Therefore, investigations on deformation behavior of the coatings under mechanical loading are of great importance. The objective of the present study was a comprehensive investigation on deformation behavior of nitride hard coatings from the coating system M‐Al‐O‐N (M = Cr, V) using nanoindentation und nanoscratch tests. In this regard, both nanoscale multilayer (nanolaminate) and monolayer coatings were investigated. All the coatings were deposited using HPPMS technology. Contrary to the expectations regarding a brittle behavior of ceramic‐like coatings, the results depict a considerable plastic deformation of the investigated hard coatings. Furthermore, in addition to a high strength, the applied coatings show a high crack resistance under mechanical loading.     

Characterization of l‐polylactide and l‐polylactide–polycaprolactone co‐polymer films for use in cheese‐packaging applications

Impact‐modified and unmodified l ‐polylactide and l ‐polylactide–polycaprolactone co‐polymer films were evaluated for their suitability as materials for cheese packaging. The polymers were in some cases compounded with nanoclays as a possible route to enhanced barrier properties and/or with cyclodextrin complexes designed to provide slow release of encapsulated antimicrobials for control of mould growth on packaged cheeses. The materials demonstrated complete biodegradation under controlled composting conditions and the extruded films had acceptable transparency. Moisture uptake by films and a decrease in polymer molecular weight with time of exposure to high humidity were identified as areas of concern, although the polymer stability experiments were undertaken at 25°C and stability at normal cheese storage temperatures (～4°C) is expected to be better. Nanoclay addition enhanced the thermal stability of the polymer but reduction of oxygen and water vapour permeability to target levels through incorporation of 5% w/w nanoclay was not achieved, possibly in part due to inadequate dispersion of the nanoclays in the chosen polymer matrices. On the positive side, a novel impact‐modified polylactide was developed that overcame problems with brittleness in unmodified l ‐polylactide and l ‐polylactide–polycaprolactone co‐polymer films, and tests indicated that a cyclodextrin‐encapsulated antimicrobial (allyl isothiocyanate) incorporated in l ‐polylactide–polycaprolactone co‐polymer films would be effective in controlling fungi on packaged cheeses. Migration of substances from the l ‐polylactide or l ‐polylactide–polycaprolactone films into cheese is not expected to be a problem. Copyright © 2005 John Wiley & Sons, Ltd.     

Improvement of Ta-based thin film barriers on copper by ion implantation of nitrogen and oxygen

Magnetron sputtered polycrystalline Ta and Ta(Si) barriers for copper metallization schemes were modified by nitrogen as well as oxygen high dose ion implantation to improve their thermo-mechanical stability. Ion bombardment changed the initial polycrystalline microstructure to amorphous-like. In contrast to pure Ta, Ta(Si) layers were already amorphous or nanocrystalline after deposition. In this case, the annealing temperature at which formation of a well crystallized structure occurs increased by approximately 100 K as a result of the implantation. In order to demonstrate the improvement in the barrier properties of the implanted Ta films, the intermixing of Ta and Cu at the interface of corresponding layer structures was measured as a function of the annealing temperature by depth profiling using Auger electron spectroscopy (AES). The thermal stability of Ta and Ta(Si) barriers increased from 600 °C/1 h for the non-implanted layers up to 750 °C/1 h after implantation of nitrogen or oxygen.     

Reversible Control of Physical Properties via an Oxygen‐Vacancy‐Driven Topotactic Transition in Epitaxial La0.7Sr0.3MnO3−δ Thin Films

The vacancy distribution of oxygen and its dynamics directly affect the functional response of complex oxides and their potential applications. Dynamic control of the oxygen composition may provide the possibility to deterministically tune the physical properties and establish a comprehensive understanding of the structure–property relationship in such systems. Here, an oxygen‐vacancy‐induced topotactic transition from perovskite to brownmillerite and vice versa in epitaxial La_0.7Sr_0.3MnO_3?δ thin films is identified by real‐time X‐ray diffraction. A novel intermediate phase with a noncentered crystal structure is observed for the first time during the topotactic phase conversion which indicates a distinctive transition route. Polarized neutron reflectometry confirms an oxygen‐deficient interfacial layer with drastically reduced nuclear scattering length density, further enabling a quantitative determination of the oxygen stoichiometry (La_0.7Sr_0.3MnO_2.65) for the intermediate state. Associated physical properties of distinct topotactic phases (i.e., ferromagnetic metal and antiferromagnetic insulator) can be reversibly switched by an oxygen desorption/absorption cycling process. Importantly, a significant lowering of necessary conditions (temperatures below 100 °C and conversion time less than 30 min) for the oxygen reloading process is found. These results demonstrate the potential applications of defect engineering in the design of perovskite‐based functional materials.     

Chemically Derived Graphene Oxide: Towards Large‐Area Thin‐Film Electronics and Optoelectronics

Chemically derived graphene oxide (GO) possesses a unique set of properties arising from oxygen functional groups that are introduced during chemical exfoliation of graphite. Large‐area thin‐film deposition of GO, enabled by its solubility in a variety of solvents, offers a route towards GO‐based thin‐film electronics and optoelectronics. The electrical and optical properties of GO are strongly dependent on its chemical and atomic structure and are tunable over a wide range via chemical engineering. In this Review, the fundamental structure and properties of GO‐based thin films are discussed in relation to their potential applications in electronics and optoelectronics.     

Einfluss der HiPIMS‐Parameter beim PVD‐Verfahren

Effect of PVD process parameters on structural properties of CrN layers Commonly, imperfections on substrate surfaces influence layer nucleation unfavorably. They cause growth defects in the coating structures prepared by physical vapor deposition. In consequence this leads to local loss of adhesion, higher friction, voids and thus favoring pitting corrosion. CrN‐coatings are known for their high hardness and good wear resistance. Further they have a better resistance to corrosion than Ti‐based nitrides. Among other parameters, the structure and the mechanical properties of those coatings can be influenced by varying bias voltage and gas flow during film growth. Due to variation of those parameters during reactive magnetron sputtering CrN‐coatings were deposited with preferred crystallized lattice orientation (111) and (200). The main objective of investigation is the potential to cover imperfections.     

氩等离子体预处理对纳米结构银非织造布抗菌性能的影响

采用磁控溅射技术，在丙纶非织造布（PP）基材表面沉积厚度为0．5-3nm的纳米结构银薄膜，重点研究了PP基材经氩等离子体预处理前后对纳米结构银薄膜抗菌性能的影响。采用振荡烧瓶法测试样品的抗菌性能，利用原子力显微镜（AFM）观察氩等离子处理前后PP基材表面的形态变化，同时应用EDX对纳米结构银薄膜进行元素分布及定量分析。实验结果表明：在纳米结构银薄膜厚度相同的条件下，经氩等离子预处理的丙纶非织造布具有更好的抗菌性能；AFM分析表明，经氩等离子处理后的纤维表面有明显的刻蚀痕迹，纤维表面凹凸不平，形成很多微小的空隙，溅射出的银粒子不易团聚，活性增加，抗菌性能因此提高；而EDX结果分析表明，抗菌性能提高是由于经氩等离子处理后，银离子溶出总量增加的缘故。     

Einfluss einer PVD‐Al‐Zwischenschicht auf die Eigenschaften eines thermisch gespritzten Wärmedämmschichtsystems nach Temperaturwechselbelastung

Thermal barrier coatings (TBC) generally consist of a metallic bond coat (BC) and a ceramic top coat (TC). Co–Ni–Cr–Al–Y metallic super alloys and Yttria stabilised zirconia (YSZ) have been widely used as bond coat and top coat for thermal barrier coatings systems, respectively. As a result of long‐term exposure of thermal barrier coatings systems to oxygen‐containing atmospheres at high temperatures, a diffusion of oxygen through the porous ceramic layer occurs and consequently an oxidation zone is formed in the interface between ceramic top coat and metallic bond coat. Alloying components of the BC layer create a so‐called thermally grown oxides layer (TGO). One included oxide type is α‐Al₂O₃. α‐Al₂O₃ lowers oxygen diffusion and thus slows down the oxidation process of the bond coat and consequently affects the service life of the coating system positively. The distribution of the alloying elements in the bond coat layer, however, generally causes the formation of mixed oxide phases. The different oxide phases have different growth rates, which cause local stresses, micro‐cracking and, finally, delamination and failure of the ceramic top coat layer. In the present study, a thin Al inter‐layer was deposited by DC‐Magnetron Sputtering on top of the Co–Ni–Cr–Al–Y metallic bond coat, followed by thermal spraying of yttria‐stabilised zirconia (YSZ) as a top coat layer. The deposited Al inter‐layer is meant to transform under operating conditions into a closed layer with high share of α‐Al₂O₃ that slows down the growth rate of the resulting thermally grown oxides layer. Surface morphology and microstructure characteristics as well as thermal cycling behaviour were investigated to study the effect of the intermediate Al layer on the oxidation of the bond coat compared to standard system. The system with Al inter‐layer shows a smaller thermally grown oxides layer thickness compared to standard system after thermal cycling under same conditions.