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In situ processing and comprehensive characterization is essential for design and development of materials used and processed at high-temperatures. Here, a new cluster tool for processing and depth-resolved compositional, structural and optical characterization of layered materials with thicknesses ranging from sub-nm to 1 μm at temperatures of -100 to 1000 °C is described [1]. The implemented techniques comprise magnetron sputtering, ion irradiation, Rutherford backscattering spectrometry, Raman spectroscopy and spectroscopic ellipsometry. The combination of techniques enables sample processing by scalable, clean, waste-free, and industry-relevant technologies, quantitative depth-profiling for elements with Z ≥ 6, structural and chemical characterization, sensitivity and nm-precise thickness and optical information for single layers, multilayers and composites. In this study, the cluster tool was used for i) metal-induced crystallization with layer-exchange of a-Si/ Ag layer stacks, and ii) for hightemperature characterization of two types of solar-selective coatings for concentrated solar power (CSP), namely Al Ti (O N )-based single and multilayers [2, 3] and an n-type doped solar-selective transparent conductive oxide [4]. Starting with an a-Si/ Ag bilayer stack, metal-induced silicon crystallization with partial layer exchange occurs at 540 °C. The final stack is approximately described by the sequence crystalline Si (c-Si)/ Ag/ c-Si. All the layers contain minor fractions of the other element. Moreover, the Si volume fraction comprises approximately 10 % of amorphous Si. For the CSP coatings, no compositional and structural changes were found up to a maximum temperature of 840 °C in vacuum. Both types of solar-selective coatings thus represent promising materials for the next generation of CSP technology. [1] R. Wenisch et al., Anal. Chem. 90, 7837-7824 (2018) [2] I. Heras et al., Sol. Energy Mat. Solar Cells, 176, 81-92 (2018) [3] R. Escobar-Galindo et al., Sol. Energy Mat. Solar Cells, 185, 183-191 (2018) [4] F. Lungwitz et al., submitted (2018) Financial support by the EU, grant No. 645725, project FRIENDS , and the HGF via the W3 program (S.G.) is gratefully acknowledged.

Metal-induced crystallization with layer exchange (MIC w LE) reduces the crystallization temperature of group 14 elements significantly. This is especially interesting for device fabrication on substrates with limited thermal stability. In this contribution, MIC w LE is applied on Ni and C thin film stacks with different stacking sequences. The influence of the thin film morphology and stacking on the layer exchange degree αLE and the graphitic ordering is studied comprehensively in situ and ex situ. During annealing of the thin films at up to 700 °C, film morphology and stacking sequence had a significant impact on αLE, showing an incomplete LE for the C/Ni stack. The highest αLE of 96%, determined by RBS and ERDA, was achieved for the smoothest samples and Ni/C stacking sequence. Raman spectroscopy and TEM demonstrated the formation of 2D crystalline carbon structures independently of the stacking sequence, while the degree of graphitic ordering increased with decreasing surface roughness. The simultaneous occurrence of LE and graphitization has been demonstrated in situ by RBS and Raman, giving insights into mechanism responsible for carbon crystallization in this system.

Metal-induced crystallization with layer exchange (MIC w LE) can reduce the crystallization temperature of group 14 elements by several hundred degrees. This is especially interesting for device fabrication on substrates with limited thermal stability. Ideally, the process allows the transfer of defined amounts of an initially amorphous material onto a randomly selected substrate. In this contribution, MIC w LE is studied for Ni/ a-C thin films with different stacking sequences in order to quantify the influence of the stacking sequence on the layer exchange degree αLE and on the degree of graphitic ordering. The process was monitored in situ by temperature-dependent Rutherford backscattering spectrometry (RBS) and Raman spectroscopy up to 700 °C. RBS, Raman, elastic recoil detection, X-ray diffraction and transmission electron microscopy were applied for ex situ characterization. The highest αLE of 96% was found for the initial Ni/a-C stacking sequence. In contrast, the inverse sequence resulted in an incomplete LE. The formation of 2D-layered carbon structures occurred independently of the initial stacking sequence.1 Beyond the threshold of 580 °C, increasing the temperature to up to 700 °C had a negligible impact on the degree of 2D-ordering. Since LE and graphitization occur simultaneously at high temperatures, MIC w LE rather than dissolution/ precipitation is proposed as responsible mechanism for carbon crystallization.

Metal-induced crystallization (MIC) with and without layer exchange (LE) is a method to decrease the crystallization temperature of amorphous group 14 elements by up to several hundred degrees. In situ experiments are expected to provide new insights into thin film evolution and elementary process steps of MIC and to improve existing models of this type of phase transformation. In this contribution in situ Rutherford backscattering spectrometry (RBS), Raman spectroscopy and spectroscopic ellipsometry studies were performed during annealing of amorphous carbon/nickel (a-C/Ni) layer stacks at temperatures up to 750°C. LE was observed independently of the initial stacking sequence, while transformation rate and temperature differ significantly. The positions of the G, D and 2D Raman lines as well as the I(D)/I(G) ratio changed during the LE process. These were assigned in agreement with the Three-Stage-Model [1], confirming the transformation of a-C to nc-graphite. In situ RBS measurements demonstrated an opposite shift of the C- and Ni- related backscattering energies, proving that LE and graphitization occur simultaneously. [1] Ferrari et al., Phys. Rev. B 61 (2000) 14095

The development of solar-selective CSP receiver coatings with high-temperature and environmental stability requires new concepts of design and in operando monitoring. Solar receiver tubes are a key component of solar thermal power plants. The increase of their operation temperature from today’s maximum of 550°C to about 800°C could increase the CSP efficiency by approximately 15 to 20% and improve the competiveness of this technology compared to other ones of carbon-free electricity generation. Potential alternatives to fast degrading state-of-the-art pigment paint receiver tube coatings are based on refractive metal carbides, nitrides, and oxides because of their high thermal stability and oxidation resistance. New types of solar-selective coatings were studied in situ at temperatures of up to 830°C by Rutherford backscattering spectrometry, Raman spectroscopy, and spectroscopic ellipsometry within a cluster tool. High-temperature stability in high-vacuum is demonstrated for carbon-metal- and oxynitride-absorber-based multilayers as well as for a solar-selective transmitter based on a transparent conductive oxide. Financial support by the EU, grant No. 645725, project FRIENDS2, and the HGF via the W3 program (S.G.) is gratefully acknowledged.

Metal-induced crystallisation with layer exchange is applied on Ni/C bilayer stacks deposited by three PVD techniques on SiO2. The layer stacks were deposited at room temperature by either ion beam sputtering, direct current magnetron sputtering or high-power impulse magnetron sputtering. The influence of the Ni morphology on the layer exchange degree aLE and the resulting graphitic ordering is studied by atomic force microscopy, Rutherford backscattering spectrometry and Raman spectroscopy. The initial RMS roughness of the Ni top layer varied with the deposition technique by a factor of 20, from 0.3 to 6.1 nm. After annealing in UHV at up to 700°C, layer exchange was observed for all samples. Still, the layer exchange degree was affected by the roughness of the initial bilayer stack. The highest value of 96% was achieved for magnetron-sputtered samples, what is by ~35% higher than for the initially roughest Ni surfaces. Raman spectroscopy showed the formation of graphitic carbon, characterised by a strong 2D line, for all three bilayer stacks. The degree of graphitic ordering increased with decreasing Ni surface roughness.

Session: Thin films type of contribution: Poster Metal-induced crystallization with and without layer exchange (MIC w/o LE) is a method to decrease the crystallization temperature of amorphous group 14 elements (G14E) by up to several hundred degrees. In situ experiments are expected to provide new insights into thin film evolution and elementary process steps of MIC w/o LE and to improve existing models of this type of phase transformation. While MIC w/o LE has been widely studied for Si and Ge in contact with catalytic metals, there exist only a few studies for the crystallization of amorphous carbon. Therefore, in this contribution in situ Rutherford backscattering spectrometry (RBS), Raman spectroscopy and spectroscopic ellipsometry studies were performed during annealing of amorphous carbon/nickel (a-C/Ni) layer stacks at temperatures up to 750°C. Due to its small lattice mismatch with the basal plane of graphite and high diffusivity of C atoms, Ni is a suitable catalyst for the growth of graphene and crystalline graphitic nanostructures. During the annealing of an a-C/Ni layer stack covalent bonds between the carbon atoms at the catalyst interface are weakened. Liberated carbon atoms can move along the interface and diffuse along the grain boundaries into the Ni layer towards the catalyst surface, where nucleation and grain growth of graphitic crystallites occur. Our in situ studies showed a change in the stacking sequence between C and Ni layers under defined experimental conditions. According to in situ Raman measurements, this mechanism occurs independent of the stacking sequence, while the velocity of the LE differs significantly. As observed in time and temperature resolved Raman spectra, the position of the G peak and the I(D)/I(G) ratio changed according to the Three-Stage-Model by Ferrari and Robertson, confirming the transformation of amorphous carbon to nc-graphite. With the in situ RBS measurements more insight into LE was given. Here peak positions of C and Ni were shifted, indicating a change of the energy of the scattered ions for both layers respectively and proving the combination of the observed graphitization process with LE during annealing. The thickness of the synthesized crystalline graphitic layer is controlled by the finite carbon source – the deposited a-C film, which is a decisive advantage of this process compared to CVD. It is demonstrated that the structure and the crystallite size of the metallic catalyst layer has a strong influence on the crystallite size and the quality of the graphitic film. LE is potentially interesting for industrial applications, as it allows the formation of polycrystalline thin films of G14E at much lower temperatures - than during thermal annealing without the metallic catalyst. Depending on the initial stacking sequence, the crystalline graphitic film can be deposited on a suitable device-ready substrate or transferred to another substrate after the dissolution of the transition metal catalyst.

The detailed knowledge of composition and microstructure is essential for the understanding of processes and properties of new materials for applications at high temperatures. To ensure materials functionality under in operando conditions, new concepts for analysis and process monitoring are necessary. In this contribution, selected PVD deposited thin film material systems were studied in situ at temperatures up to 830°C by Rutherford backscattering spectrometry (RBS), Raman spectroscopy, and spectroscopic ellipsometry (SE) within a cluster tool. Metal-induced crystallization with and without layer exchange (MIC w/o LE) is an emerging technique for processing of amorphous group IV elements below their isothermal crystallization temperatures. In this study, a bilayer system of 60 nm amorphous Si covered by 30 nm Ag (a-Si/Ag) was annealed at temperatures of 380 to 700°C by the combination of the above mentioned in situ techniques. The process comprised a relatively long-term incubation period followed by a fast MIC w/o LE step. More than 90% of the initial a-Si could be crystallized on top of the Ag-layer for optimized process conditions with temperatures of about 550°C. The as-formed Si consisted of up to 95% crystalline Si. As an example for high-temperature solar selective coatings for thermo-solar applications, AlTiN and AlTiN1-xOx (x = 0 - 0.2) thin films were investigated in order to understand the influence of the oxygen/nitrogen ratio on the optical properties and failure mechanisms at high temperatures. The elemental depth profiles and the phase structure of both coatings do not change during annealing in high vacuum at temperatures up to of 750°C, as revealed by unchanged RBS and Raman spectra, respectively. SE and RBS results showed the influence of the initial oxygen content on high temperature stability of AlTiN and AlTiN1-xOx thin films. The low emittance of AlTiN1-xOx, allowed performing in situ RBS analysis at temperatures up to 830°C for the first time.

Metal-induced crystallization with and without layer exchange (MIC w/o LE) is a method to decrease the crystallization temperature of amorphous group 14 elements (G14E) by up to several hundred degrees. In situ experiments are expected to provide new insights into thin film evolution and elementary process steps of MIC w/o LE and to improve existing models of this type of phase transformation. While MIC w/o LE has been widely studied for Si and Ge in contact with catalytic metals, there exist only a few studies for the crystallization of amorphous carbon. Therefore, in this contribution in situ Rutherford backscattering spectrometry (RBS), Raman spectroscopy and spectroscopic ellipsometry studies were performed during annealing of amorphous carbon/nickel (a-C/Ni) layer stacks at temperatures up to 750°C. Due to its small lattice mismatch with the basal plane of graphite and high diffusivity of C atoms, Ni is a suitable catalyst for the growth of graphene and crystalline graphitic nanostructures. During the annealing of an a-C/Ni layer stack covalent bonds between the carbon atoms at the catalyst interface are weakened. Liberated carbon atoms can move along the interface and diffuse along the grain boundaries into the Ni layer towards the catalyst surface, where nucleation and grain growth of graphitic crystallites occur. Our in situ studies showed a change in the stacking sequence between C and Ni layers under defined experimental conditions. According to in situ Raman measurements, this mechanism occurs independent of the stacking sequence, while the velocity of the LE differs significantly. As observed in time and temperature resolved Raman spectra, the position of the G peak and the I(D)/I(G) ratio changed according to the Three-Stage-Model by Ferrari and Robertson, confirming the transformation of amorphous carbon to nc-graphite. With the in situ RBS measurements more insight into LE was given. Here peak positions of C and Ni were shifted, indicating a change of the energy of the scattered ions for both layers respectively and proving the combination of the observed graphitization process with LE during annealing. The thickness of the synthesized crystalline graphitic layer is controlled by the finite carbon source – the deposited a-C film, which is a decisive advantage of this process compared to CVD. It is demonstrated that the structure and the crystallite size of the metallic catalyst layer has a strong influence on the crystallite size and the quality of the graphitic film. LE is potentially interesting for industrial applications, as it allows the formation of polycrystalline thin films of G14E at much lower temperatures - than during thermal annealing without the metallic catalyst. Depending on the initial stacking sequence, the crystalline graphitic film can be deposited on a suitable device-ready substrate or transferred to another substrate after the dissolution of the transition metal catalyst.

Metal induced crystallization (MIC) is a promising technique for low-temperature thin film transistor fabrication and graphene synthesis. In MIC, a transition metal catalyzes the crystallization of the amorphous phase of a group IV element by bond screening near the interface and facilitation of nucleation. So far, in situ studies have been performed using X-ray diffraction, which is sensitive to the degree of crystallinity. In situ Rutherford backscattering spectrometry has the advantage of elemental depth resolution and time resolved tracking of diffusion and layer exchange processes. Graphene formation through MIC has been demonstrated with an a-C/Ni layer stack [1]. As a model system for MIC, the Si/Ag bilayer system is studied here. The Si/Ag layer stacks are annealed at temperatures of 380 to 700 °C. Depth profiles of the elements are investigated by in situ RBS. Their analysis reveals the diffusion kinetics of the elements. The changes in the phase structure are explored by in situ Raman spectroscopy. Both the quick initial nucleation and ensuing growth processes are investigated. [1] Weatherup et al., Nano Letters 13, pp. 4624 (2013)

The detailed knowledge of composition and structure is essential for the understanding of processes and properties of functional materials at elevated temperatures. To ensure materials functionality under in operando conditions, new concepts for analysis and process monitoring are necessary. In this contribution, selected layered material systems were studied in situ at temperatures up to 830°C by Rutherford backscattering (RBS), Raman spectroscopy, and ellipsometry within a cluster tool. Metal induced crystallization (MIC) is a promising technique for hydrogen-free synthesis of two-dimensional materials. Here, Si/Ag bilayers are studied as model system. The Si/Ag layer stacks are annealed at temperatures of 380 to 700°C. simultaneously, depth profiles of the elements are investigated by RBS revealing the diffusion kinetics. The changes in the phase structure and the degree of crystallinity are analyzed by Raman spectroscopy. Both the quick initial nucleation and ensuing growth processes are investigated. MIC is observed for all temperatures under study, while layer exchange occurs only for optimized process conditions. As an example for high-temperature functional coatings, AlTiOxN1-x thin films were investigated in order to understand the influence of the oxygen to nitrogen ratio on the optical properties and their failure mechanisms at high temperatures. Ellipsometry and RBS results showed the influence of the initial oxygen content in the sample, inward diffusion of oxygen into the coating, and the high temperature stability of AlTiOxN1-x thin films. The low emittance of AlTiOxN1-x, allowed performing in situ RBS analysis at temperature up to 830°C for the first time. Financial support by the EU, grant No. 645725, project FRIENDS2, and the HGF via the W3 program (S.G.) is gratefully acknowledged.

Compatibility with commonly used substrate materials is of crucial importance for graphene device production. Low-temperature synthesis approaches are needed to cope with this challenge. Therefore it has to be clarified, to which extend physical vapor deposition can be used to produce ordered graphene structures. In this contribution, the mechanism of graphitic ordering of atomic C on Ni was investigated at temperatures ranging from room temperature to 550 °C. The C/Ni films were prepared by ion beam sputtering. A temperature-induced and a Ni-induced enhancement of graphitic ordering is demonstrated. The Ni-effect is responsible for the formation of a bi-layer structure of the C films at higher deposition temperatures. In the bi-layers, C forms graphenic planes parallel to the Ni surface within a thickness range of 1-2 nm. Further deposited C grows preferentially perpendicular to the surface. The results are discussed on the basis of hyperthermal atom deposition, surface diffusion, metal-induced crystallization and dissolution-precipitation. Our findings point to a dominating role of surface diffusion-assisted crystallization in the carbon ordering process.

Aluminum-titanium oxynitride AlTiO(x)N(y) thin films were investigated in order to understand the influence of the oxygen/nitrogen ratio on the optical properties and their failure mechanisms at high temperatures. The optical properties of oxynitride thin films as well as their high temperature stability showed a wide range of different responses according the oxygen/nitrogen ratio and the deposition pressure. AlTiO(x)N(y) thin films were deposited by cathodic vacuum arc and characterized at different temperatures to follow the temperature dependence of the composition and the optical constants. The samples were heated in vacuum from room temperature up to 800°C inside a multi-chamber cluster tool and the analysis of the thin films was carried out in-situ without intermittent sample exposure to air. Ellipsometry and Rutherford backscattering spectrometry (RBS) results showed the influence of the as-deposited oxygen content in the sample with the inward diffusion of oxygen into the coating and therefore oxidation resistance at high temperatures. Likewise, ex-situ annealing in air was performed to compare the results observed when exposed to ambient conditions. The low emittance properties of AlTiO(x)N(y) enabled in-situ RBS analysis at temperatures higher than 750°C. No significant changes of the optical properties and composition were found when heating in vacuum demonstrating excellent stability at high temperatures.

AlTiN, AlTiO, and AlTiO(x)N(y) thin films were investigated in order to understand the influence of the oxygen to nitrogen ratio on the failure mechanisms at high temperatures. The thin films were deposited by cathodic vacuum arc and characterized in-situ following the methodology proposed for comprehensive environmental testing of optical properties in thin films using the HZDR cluster tool [1]. This multi-chamber material processing and analysis system enables the detailed analysis of the temperature dependence of composition, chemical bonding, and optical properties of thin films. The methodology combines the sequential study of the optical constants by spectroscopic ellipsometry, compositional analysis using ion beam analysis techniques and structure analysis by Raman spectroscopy. All characterizations of AlTiO(x)N(y) thin films were carried out in situ without sample exposure to undefined atmospheres. The samples were heated in vacuum from room temperature to 800°C inside the different chambers and in parallel, to elucidate the influence of the ambience on the degradation process. Moreover, ex-situ annealing in air was performed. Ellipsometry, Raman and ERDA results show the influence of the initial oxygen content in the sample with the inward diffusion of oxygen into the coating and the oxidation resistance at high temperatures. [1] I. Heras, E. Guillén, R. Wenisch, M. Krause, R. Escobar Galindo, J.L. Endrino - Comprehensive environmental testing of optical properties in thin films. Procedia CIRP. 22 (2014) 271–276

Metal induced crystallization (MIC) is a promising technique for thin film transistor fabrication and graphene synthesis. In MIC, a transition metal catalyzes the crystallization of the amorphous phase of a group IV element by bond screening near the interface and facilitation of nucleation. So far, in situ studies have been performed using X-ray diffraction which is sensitive to the degree of crystallinity. However this technique lacks depth resolution and is therefore unable to track diffusion and layer exchange. Here, the Si/Ag and C/Ni bilayer systems are studied. The samples are annealed at temperatures of up to 750 °C. Simultaneously, depth profiles of the elements are investigated by in situ Rutherford backscattering spectroscopy revealing the diffusion kinetics. The changes in the phase structure are explored by in situ Raman spectroscopy. Both the quick initial nucleation and ensuing growth processes are investigated. Scanning electron microscopy provides insight to the surface morphology.

Metal induced crystallization (MIC) is a promising technique for low temperature thin film transistor fabrication and graphene synthesis. In MIC, a transition metal acts as seed for the crystallization of an amorphous group IV element. Bond screening near the interface and facilitation of nucleation are recently discussed as mechanisms for MIC. So far, in situ studies have been performed using X-ray diffraction, which is sensitive to the degree of crystallinity but lacks depth resolution. A better insight into the MIC mechanisms requires depth resolved in situ studies in order to determine the concentration profiles of the diffusing components. Here, the Si/Ag and C/Ni bilayer systems are studied. They are annealed at temperatures of up to 750 °C. Simultaneously, the layer composition and the compositional profiles are investigated with in situ Rutherford backscattering spectroscopy revealing the diffusion kinetics of the components. Both, the quick initial nucleation and the ensuing growth processes are investigated. Further characterization is performed employing in vacuo Raman spectroscopy revealing the phase structure of the resulting films and scanning electron microscopy to investigate the surface structure.

Transparent conductive oxides (TCOs) are already widely used in the optoelectronic industry e.g. as electrodes for liquid crystal displays (LCDs), organic light emitting diodes (OLEDs), or thin film solar cells. Less attention has been devoted to their optical properties and thermal stability until now. In this work, Tantalum doped TiO2 and SnO2 TCO films are investigated with respect to their structural, optical, and electrical properties at temperatures from RT to 700°C. The films are prepared at room temperature by direct current reactive magnetron sputtering from metallic as well as ceramic targets and subsequently isothermally annealed at temperatures of 425°C. For compositional and structural analysis x-ray diffraction (XRD), Raman spectroscopy, and Rutherford backscattering spectroscopy (RBS) are used. The optical properties are determined by spectroscopic ellipsometry, spectral photometry, and subsequent modelling. Hall effect measurements are used to determine the electrical properties of the TCO films. The as-deposited layers are amorphous and isolating. By thermal annealing they are activated and become conductive.

Moderne Werkstoffe sind bei vielen Anwendungen extremenUmgebungsbedingungen ausgesetzt. Dazu zählen hohe und tiefe Temperaturen bzw. große Temperaturschwankungen, die teilweise in Verbindung mit korrosiven oder reaktiven Atmosphären oder hohen mechanischen Belastungen auftreten. Sie stellen hohe Anforderungen an die Beständigkeit und Stabilität der verwendeten Werkstoffe. Als Beispiele seien solarselektive Absorber, Komponenten des Antriebsstranges von Verbrennungsmotoren und Rotoren von Turboladern und Turbinen genannt. Die Gewährleistung der Werkstofffunktionalität über die gesamte Lebensdauer erfordert neue Konzepte der Analyse und Prüfung. Dazu wurde am 6MV Ionenbeschleuniger des HZDR mit Fördermitteln des Impuls- und Vernetzungsfonds des Präsidenten der HGF sowie des KFSI ein Cluster-Tool zur in situ Modifizierung und Analyse von Werkstoffen bei Temperaturen von bis zu 1000°C, unter korrosiven Atmosphären und mechanischem Verschleiß aufgebaut. Kernbestandteil des Cluster-Tools ist eine zentrale Hochvakuum (HV)-Probenaufnahme- und Transferkammer. Diese ist mit weiteren HV-Kammern verbunden, in denen die sequentielle Probensynthese und -modifizierung, die Element- und Strukturanalytik und die optische Charakterisierung erfolgt, ohne das Vakuum zu brechen und die Werkstoffe undefinierten Umgebungsbedingungen auszusetzen. In allen Kammern besteht die Möglichkeit, in situ Heizexperimente bei Temperaturen von bis zu 1000°C durchzuführen. Die mit dem 6MV Tandem-Ionenbeschleuniger verbundene Kammer zur Ionenstrahlanalytik ermöglicht die Untersuchung der Elementzusammensetzung durch Rutherford Rückstreuung und Nuklearer Reaktionsanalyse. Die Schichtzusammensetzung kann bis in eine Tiefe von ca. 1μm auf bis zu 10 nm genau bestimmt werden. Bei Hochtemperaturuntersuchungen reduziert sich die Tiefenauflösung auf etwa 25 nm. Zur strukturellen Charakterisierung der Proben dient ein fasergekoppeltes Ramanspektrometer an der Analysenkammer des Cluster-Tools, dessen Probenkopf über eine Kamera auch die visuelle Beurteilung der Proben ermöglicht. Die Untersuchung der optischen Eigenschaften und deren Abhängigkeit von Temperatur und Atmosphäre erfolgt durch spektroskopische Ellipsometrie in einer Umweltkammer, in der korrosive Umgebungen simuliert werden können. Für 2015 ist die Installation eines in situ Tribometers in Vorbereitung, mit dem das Reib- und Verschleißverhalten von Werkstoffen unter definierten Atmosphären untersucht werden kann. Zusammengefasst entsteht mit dem Cluster-Tool am 6 MV Ionenbeschleuniger des HZDR ein Messplatz zur umfassenden in situ Modifizierung und Analyse von Werkstoffen, mit Hilfe dessen komplexe Probenbehandlungsprotokolle unter extremen Umgebungsbedingungen bearbeitet werden können.

Interface dynamics play a crucial role in Nickel catalyzed fabrication of carbon nanotubes, carbon nanowires and graphene. Interface dynamics are studied by deposition of atomic C on Ni at temperatures of 23–550°C. The obtained films are characterized by transition electron microscopy, Raman-spectroscopy, nuclear reaction analysis and X-ray photoelectron spectroscopy. Bulk diffusion and solubility are found negligible in the present experiments leaving surface diffusion as the main graphitization mechanism. The presented process may open new avenues for the fabrication of graphene on Ni at low temperatures (< 300°C).

Interface dynamics play a crucial role in the Nickel catalyzed synthesis of carbon nanotubes, carbon nanoribbons and graphene. Interface dynamics are studied by deposition of atomic C on Ni at temperatures of 23−550°C. The obtained films are characterized by transition electron microscopy, Ramanspectroscopy, nuclear reaction analysis and X-ray photoelectron spectroscopy. Bulk diffusion and carbon dissolution are found to be negligible under the chosen experimental conditions leaving surface/interface diffusion as the main graphitization mechanism. Graphitic ordering starts at ~ 250°C and increases further at temperatures > 500°C. The initial graphitization occurs parallel to the Ni surface. As the growth continues, additional atomic planes turn perpendicular. First results are shown for the Si-Ag system processed under similar deposition conditions.

Crystallization kinetics of ion beam sputtered carbon on polycrystalline nickel thin films is investigated. The process temperature is significantly reduced in comparison to annealing of an amorphous carbon film without the aid of a transition metal. The degree of graphitization and the average grain size of the resulting films are examined by means of Raman-spectroscopy and high resolution transmission electron microscopy. The chemical state of the carbon atoms is analyzed by X-ray photoelectron spectroscopy. Additionally, nuclear reaction analysis confirms the temperature independence of the carbon absorption on the nickel surface. We believe that the process holds a potential for the synthesis of crystalline thin films or single layers of different 2D nanomaterials.

The mechanical and tribological properties of nanostructured carbon:nickel films on silicon substrates are investigated using a multi-scale experimental and theoretical approach. The C:Ni nanostructures comprising either tilted columns or three-dimensionally self-organized nanopatterns are grown by ion-beam assisted deposition (IBAD). Complex layer architectures were obtained by sequential deposition by rotating the substrate in relation to the assisting ion beam after each deposition step. Atomic composition of the films was determined by ion beam analysis. The phase structure of carbon was analyzed by Raman spectroscopy, that of nickel by X-ray diffraction. The microstructure of the films was determined by high resolution transmission electron microscopy. The films show good adhesion as probed by scratch tests. The film hardness is on the order of 20 GPa, and the elastic modulus is at about 200 GPa. Friction coefficients on the order of 0.1 are found for oscillating wear conditions under ambient conditions. Atomistic computer simulations were applied to assist the experimental findings. Dry and liquid contacts are considered. The simulation shows a complex behaviour for the carbon-carbon interaction, e.g. resulting in the formation of a tribo-layer.

Precise control of single walled carbon nanotube (SWCNT) diameter, chirality, alignment, and intertube arrangement are still remaining challenges in the catalytic chemical vapour deposition (CCVD) synthesis. In this context it has still to be clarified whether a predefined size and shape of the nanoparticles can be stabilized by a suitable matrix material while preserving the catalytic activity of the metal. For this study Ni nanoparticles were encapsulated in an amorphous carbon matrix by physical vapour deposition. As prepared Ni catalysts were used for CNT fabrication by laser assisted CVD applying either no external carbon source or C2H4 gas, and by low pressure CVD applying C2H2 or CH4 as carbon source. The broad range of CNT synthesis conditions indicates the robustness of the embedded Ni particles as a catalyst for carbon nanotube formation. SEM and laser wavelength dependent Raman spectroscopy were used for CNT characterisation. The nickel-SWCNT-interaction was modelled by density functional calculations with the projector augmented plane wave method, utilizing the generalized gradient approximation for the exchange-correlation functional.

Current perovskite solar cell efficiency is close to silicon's record values. Yet, the roadblock for industrialization of this technology is its stability. The stability of the solar cell not only depends on the stability of the perovskite material itself but also notably on its contact layers and their interface with the perovskite, which plays a paramount role. This study rationalizes the design of new molecules to form self-assembled monolayers as a hole-selective contact. The new molecules increased the stability of the perovskite solar cells to maintain 80% of their initial PCE of 21% for 250 h at 85 °C under 1 sun illumination. The excellent charge collection properties as well as perovskite passivation effect enable the highly stable and efficient devices to demonstrate the vast potential of this new type of contact in photovoltaic application.