The aim of this thesis is to interconnect human tactile perception with various physical properties of materials. Tactile perception necessitates contact and relative motion between the skin and the surfaces of interest. This implies that properties such as friction and surface roughness ought to be important physical properties for tactile sensing. In this work, a method to measure friction between human fingers and surfaces is presented. This method is believed to best represent friction in tactile perception. This study is focused on the tactile perception of printing papers. However, the methodology of finger friction measurements, as well as the methodology to link physical properties with human perception data, can be applied to almost whichever material or surfaces.   This thesis is based on three articles.   In Article I, one participant performed finger friction measurements, using a piezoelectric force sensor, on 21 printing papers of different paper grades and grammage (weight of the papers). Friction coefficients were calculated as the ratio of the frictional force and the normal force, shown to have a linear relationship. The values were recorded while stroking the index finger over the surface. The results show that measurements with the device can be used to discriminate a set of similar surfaces in terms of finger friction. When comparing the friction coefficients, the papers group according to paper surface treatment and an emerging trend is that the rougher (uncoated) papers have a lower friction coefficient than the smoother (coated) papers. In the latter case, this is interpreted in terms of a larger contact between the finger and paper surface.   In addition, a decrease in friction coefficient is noted for all papers on repeated stroking, where the coated papers display a larger decrease. XPS (X-ray Photoelectron Spectroscopy) reveals that skin lipids are transferred from the finger to the paper surface, acting as a lubricant and hence decrease friction. Nevertheless, there is evidence that mechanical changes of the surface cannot be completely ruled out.   The reproducibility of the finger friction measurements is elaborated in Article II, by using many participants on a selection of eight printing papers out of the 21. The trends in friction are the same; once again, the coated papers display the highest friction. There are notably large variations in the exact value of the friction coefficient, which are tentatively attributed to different skin hydration and stroking modes.   These same participants also took part in a tactile study of perceived paper coarseness (“strävhet” in Swedish). The results reveal that the participants can distinguish a set of printing papers in terms of perceived coarseness. Not unexpectedly, surface roughness appears to be an important property related to perceived coarseness, where group data display that perceived coarseness increases with increasing surface roughness. Interestingly, friction also appears to be a discriminatory property for some subjects. A few participants showed opposite trends, which is evidence for that what is considered coarse is subjective and that different participants “weigh” the importance of the properties differently. This is a good example of a challenge when measuring one-dimensional perceptions in psychophysics.   In Article III, a multidimensional approach was used to explore the tactile perception of printing papers. To do this, the participants scaled similarity among all possible pairs of the papers, and this similarity data are best presented by a three-dimensional space solution. This means that there are three underlying dimensions or properties that the participants use to discriminate the surface feel. Also, there is a distinct perceptual difference between the rougher (uncoated) and smoother (coated) papers. The surface roughness appears to be the dominant physical property when discriminating between a real rough paper and a smooth paper, whereas friction, thermal conductivity and grammage are more important when discriminating among the smooth coated papers.

Graphene has been considered for a variety of applications including novel nanoelectronic device concepts. However, the deposition of ultra-thin high-k dielectrics on top of graphene has still been challenging due to graphene's lack of dangling bonds. The formation of large islands and leaky films has been observed resulting from a much delayed growth initiation. In order to address this issue, we tested a pre-treatment with NF³ instead of XeF² on CVD graphene as well as epitaxial graphene monolayers prior to the Atomic Layer Deposition (ALD) of Al²O³. All experiments were conducted in vacuo; i. e. the pristine graphene samples were exposed to NF³ in the same reactor immediately before applying 30 (TMA - H²O) ALD cycles and the samples were transferred between the ALD reactor and a surface analysis unit under high vacuum conditions. The ALD growth initiation was observed by in-situ real-time Spectroscopic Ellipsometry (irtSE) with a sampling rate above 1 Hz. The total amount of Al²O³ material deposited by the applied 30 ALD cycles was cross-checked by in-vacuo X-ray Photoelectron Spectroscopy (XPS). The Al²O³ morphology was determined by Atomic Force Microscopy (AFM). The presence of graphene and its defect status was examined by in-vacuo XPS and Raman Spectroscopy before and after the coating procedure, respectively.

Der Schwerpunkt der vorliegenden Arbeit liegt in der Charakterisierung der elektronischen Eigenschaften von hybriden organisch-anorganischen Perowskit (HOIP)-Schichten während der Schichtbildung und in verschiedenen Umgebungen mittels Photoelektronenspektroskopie (PES). Insbesondere wird der Methylammonium-Blei-Iodid-Chlorid-Perowskit (MAPbI3-xClx) untersucht. Als erstes werden Änderungen in den elektronischen Eigenschaften, der Zusammensetzung, sowie der Kristallstruktur mittels PES, Flugzeit-Sekundärionenmassenspektrometrie, sowie Röntgendiffraktometrie mit streifendem Einfall analysiert. Die Resultate weisen auf die entscheidende Rolle von Chlor im texturierten Wachstum der Perowskitschicht hin. Die auskristallisierte Perowskitschicht weist eine stärkere n-Typ Eigenschaft auf, welche auf die Änderung der Zusammensetzung während der Schichtbildung zurückgeführt werden kann. Außerdem beweisen die Ergebnisse eindeutig die Ablagerung von Chlor an der Grenzfläche zwischen der Perowskitschicht und dem Substrat. Zweitens werden die separaten Einflüsse von Wasser, Sauerstoff, und Umgebungsluft auf die elektronischen Eigenschaften von MAPbI3-xClx-Schichtoberflächen untersucht. Bereits geringste Wassermengen ähnlich wie im Hochvakuum oder in inerter Umgebung können eine reversible Reduzierung der Austrittsarbeit hervorrufen. Höherer Wasserdampf-Partialdruck führt zu einer Verschiebung des Valenzbandmaximums (VBM) weit vom Fermi-Niveau, sowie zu einer Reduzierung der Austrittsarbeit. Im Gegensatz dazu führt eine Sauerstoffexposition zu einer Verschiebung des VBM in Richtung des Fermi-Niveaus und zu einer Steigerung der Austrittsarbeit. Analog kommt es zu einer Verschiebung von bis zu 0.6 eV bei einer Exposition gegenüber Umgebungsluft, was den vorwiegenden Einfluss von Sauerstoff demonstriert. Die vorliegenden Untersuchungen betonen den kritischen Einfluss der Schichtbildung, der Zusammensetzung, sowie der Umgebungsbedingungen auf die elektronischen Eigenschaften von HOIP. / The present thesis aims at characterizing the electronic properties of solution-processed hybrid organic-inorganic perovskites (HOIPs) in general, and the HOIP methyl ammonium (MA) lead iodide-chloride (MAPbI3-xClx) films, in particular, at different stages, namely from its formation to its degradation, by means of photoelectron spectroscopy (PES). Firstly, the formation of MAPbI3-xClx films upon thermal annealing is monitored by a combination of PES, time-of-flight secondary ion mass spectrometry, and grazing incidence X-ray diffraction for disclosing changes in electronic properties, film composition, and crystal structure, respectively. Overall, the results point to the essential mediating role of chlorine in the formation of a highly textured perovskite film. The film formation is accompanied by a change of composition which leads to the film becoming more n-type. The accumulation of chlorine at the interface between perovskite and the underlying substrate is also unambiguously revealed. Secondly, the separate effects of water and oxygen on the electronic properties of MAPbI3-xClx film surfaces are investigated by PES. Already low water exposure – as encountered in high vacuum or inert conditions – appears to reversibly impact the work function of the film surfaces. Water vapor in the mbar range induces a shift of the valence band maximum (VBM) away from the Fermi level accompanied by a decrease of the work function. In contrast, oxygen leads to a VBM shift towards the Fermi level and a concomitant increase of the work function. The effect of oxygen is found to predominate in ambient air with an associated shift of the energy levels by up to 0.6 eV. Overall, the findings contribute to an improved understanding of the structure-property relationships of HOIPs and emphasize the impact of least variation in the environmental conditions on the reproducibility of the electronic properties of perovskite materials.

Oxidische Materialien bieten ein weites Spektrum an möglichen Anwendungen. Vor allem Isolatoren mit Perowskitstruktur eignen sich hervorragend für die optische Datenverarbeitung und -speicherung. Andere, leitende, Oxide können für die magnetische Datenspeicherung eingesetzt werden. Vorraussetzung für den praktischen Einsatz der Werkstoffe sind jedoch grundlegende Kenntnisse über deren mikroskopischen Eigenschaften und ablaufende Prozesse. Mittels Photoelektronen- und Röntgenspektroskopie können Aussagen über die elektronische Struktur getroffen werden. Die noch junge Methode der Fluoreszenz weicher Röntgenstrahlung (SXF) wurde zur Charakterisierung der elektronischen Struktur hinzugezogen. SXF-Messungen wurden an der Beamline 8.0.1 am ALS in Berkeley, Kalifornien, durchgeführt. An der Modellsubstanz MgO wurden Röntgenabsorptions- und Röntgenemissionsspektren an der Sauerstoffkante erstellt. Es zeigt sich eine hervorragende Übereinstimmung mit Modellrechnungen. Ein Bandmapping unter Ausnutzung von Resonanzphänomenen, ähnlich wie in Graphit, scheint jedoch nicht möglich zu sein. In TiO2 wurde das Ti 3d Niveau untersucht. Die Emissionsspetkren zeigen Verluststrukturen, deren Feinstruktur mit der berechneten rJDOS nachvollzogen werden konnte. In KNbO3 wurde der Beitrag der Nb 5p und O 2p-Zustandsdichte zum Valenzband untersucht. Es wurde versucht, die Anregungsenergieabhängigkeit der O 2p-Emissionsspektren mit der Bandstruktur in Verbindung zu bringen. In KTaO3 wurde erstmals der Ta 5d-pDOS-Anteil am Valenzband direkt nachgewiesen. Zudem weisen die anregungsenergieabhängigen Emissionsspektren Verluststrukturen auf, die auf eine O 2p-Ta 5d Interbandanregung schließen lassen. An Sr2FeMoO6 wurden erstmals XES-Messungen zur Bestimmung der elektronischen Struktur durchgeführt. Es zeigen sich hybridisierte O 2p-Mo 4d Zustände, die Leitungselektronen haben einen leichten Fe-Charakter. Eine gute Übereinstimmung mit Bandstrukturrechnungen wird beobachtet. Für photorefraktive Material Sn2P2S6 wurde die elektronische Struktur mittels XPS, XES und FP-LAW-Rechnungen detailliert bestimmt. An Fe-dotiertem Ba0.77Ca0.23TiO3 wurde mittels XPD unter erstmaliger Erstellung von Azimuthalspektren der Einbauplatz von Ca verifiziert und der Einbauplatz von Eisen bestimmt. Für beide Elemente ergibt sich ein vollständiger bzw. überwiegender Einbau auf dem Ba-Platz.

Diese Arbeit beschäftigt sich mit der Herstellung von organischen selbstorganisierenden (Sub-)Monolagen (sog. SAM s) auf Siliziumoxid und deren Metallisierung. Die characteristischen Strukturen dieser Oberflächen sind mit der Rasterkraftmikroskopie (RKM) untersucht worden. Im präparativen Abschnitt wird die Abscheidung des SAM (Octadecyltrichlorosilan (OTS)) in einer Toluol/Wasserlösung auf eine Siliziumoxidoberfläche und deren anschließendem lateralen Erscheinungsbild (als Octadecylsiloxan ODS) beschrieben. Die Submonolagen des ODS auf dem Oxid erscheinen in den Topografiebildern des RKM s als eine Art Insellandschaft . Diese Modellstrukturen mit stark unterschiedlicher Oberflächeneigenschaften sind in dem methodischen Teil der Arbeit unter verschiedenen äußeren Bedingungen untersucht worden. Neben der Lateralkraft (Kontakt-Modus) und der Dämpfung (dyn. Nichtkontakt-Modus) stand hier die Kontrastentstehung der Topografie im RKM im Vordergrund. Im Gegensatz zu der theoretischen Länge des ODS-Moleküls wurde eine geringere Höhe des adsorbierten Moleküls gemessen. Im zweiten Teil dieser Arbeit wurde untersucht, wie die ODS-(Unter)Struktur das Wachstum aufgedampfter Metallschichten beeinflusst. Die Ergebnisse der Evaporation mit Silber und Eisen ergaben zum Teil überraschende Ergebnisse. Frisch aufgedampfte Filme ließen die Unterstruktur anhand der Größe der Metallcluster erkennen, wobei das Silber auf ODS größere Cluster bildete als Eisen auf ODS. Nach einer Temperaturbehandlung unterscheiden sich die Systeme sehr stark, im Falle des Fe-Substrates invertierte sich der Kontrast der Topografie.

The presented thesis includes investigations to fully characterize the electronic structure and magnetic properties ofselected manganese containing high-spin molecules by means of various X-ray spectroscopic, magnetic and theoretical methods. The investigations on the Mn4 star-shaped molecule havelead to a number of interesting results. Magneto-chemical studies exhibit very weak exchange coupling constantsbetween the four Mn(II) ions, leading to complicated low lying states in which the ground state is not well separated, resulting from a dominant weak ferromagnetic coupling and a giant moment of up to 20 µB/f.u. XMCD measurements revealed that almost the completemagnetic moment is located around the Mn(II) ions.This is in agreement with only a few charge transfer states foundwithin the detailed X-ray absorption spectroscopic study. The electronic structure and detailed magnetic properties of the star-shaped heteronuclear CrIIIMnII3 complex have been precisely investigated.With XPS the homovalency of Mn and Cr have been verified. The XA-spectra of the manganese and chromium L edges were measured and compared to earlier investigated Mn4 spectra.The combination high-magnetic field magnetic measurements and element selective XMCD of Mn and Cr L edges and quantum model calculations lead to a complete analysis of the magnetic structure of the CrMn3 magnetic core. The III valence state of the manganese ions in MnIII6O2Salox has been verified. From X-ray diffraction, typical Jahn-Teller distorted oxygen octahedra have been found for Mn(III) ions. Comparisons of XPS and XAS spectra of the complex to corresponding spectraof maganite and tetranuclear manganese(II) cluster it was definitely possible to identify MnIII6O2Salox as a pure Mn(III) compound.

The aim of the present work was to develop a detailed picture of the electronic and magnetic properties of a number of interesting transition metal compounds. A number of complementary experimental and theoretical techniques have been applied, special emphasis was given to x-ray spectroscopies. The studies led to a number of results, and the following conclusions can be drawn: The influence of the magnetic ground state (high-spin (FeO) vs. low-spin (FeS2)) with respect to the recorded x-ray spectra was investigated. In particular, by performing RXES on the Fe L edge of the two compounds, very different ratios of La / Lβ integrated intensity for excitation energies close to the L2 edge have been observed. This effect has been explained in terms of the magnetic structure of FeO (high spin), which inhibits Coster-Kronig processes. Special attention has been given to the direct investigation of orbital ordering in a three dimensional CMR manganite, namely La7/8Sr1/8MnO3, by means of x-ray linear dichroism (XLD). We obtained, for the first time, rather strong indications that the coherently distorted Jahn-Teller phase in La7/8Sr1/8MnO3 is accompanied by a predominantly cross type (x2-z2) / (y2-z2) orbital ordering. In addition to manganites the double perovskite Sr2FeMoO6 the combined study by means of x-ray spectroscopies, magnetic measurements and theoretical band structure calculations could resolve some points discussed controversially in the literature. Both, paramagnetic measurements as well as core level spectroscopy of the Fe 2p, Fe 3s and the Mo 3d states suggest a mixed iron valence state involving around 30% Fe3+- Mo5+ and 70% Fe2+ - Mo6+ states in highly ordered Sr2FeMoO6. XPS valence band studies reveal that the Fe 3d states are not extremely localized, and we find evidence that charge transfer between Fe 3d and O 2p states plays an essential role.

The subject of this work subscribes to the international preoccupation regarding the elucidation of magnetic properties of solids. The crystallographic, electronic and magnetic structures of Al-Mn-Ni alloys and compounds have been investigated by X-ray diffraction, magnetization and magnetic susceptibility measurements, X-ray photoelectron spectroscopy (XPS), and band structure calculations. The thesis is organized in 6 Chapters, followed by the summary. Chapter 1 contains a brief theoretical introduction into the magnetism of metallic systems, as well the principles of XPS. The sample preparation details and all the techniques employed in the characterization of the systems are described in Chapter 2. The next 4 Chapters contain the experimental results for Mn1-xAlxNi3, Mn1-xAlxNi, Ni1-xMnxAl, Ni0.7-xAlxMn0.3 systems.

La génération de surfaces présentant des nanostructurations de surface variées et modulables est l’objectif principal de ce travail. L’auto-assemblage de copolymères à bloc ou de nanoparticules d’or a été privilégié, et nécessite pour se faire de moduler finement les interactions aux interfaces substrat/ matériaux déposés. Dans une première partie, un dispositif expérimental de greffage de silane alkyle en voie vapeur est décrit. Cette technique de greffage permet d’aboutir à des surfaces fonctionnalisées soit de façon homogène, soit de façon graduelle et ce, avec un ou deux silanes (substrat respectivement mono ou bi-composant). La robustesse, la simplicité et la flexibilité de notre procédé ont été démontrés par des caractérisations physico-chimique (mesure des propriétés de mouillabilité), chimique (spectroscopie de photoélectrons X) ainsi que par analyse topographique (microscopie à force atomique). Dans une deuxième partie, l’influence des interactions aux interfaces substrat / film sur l’auto-assemblage de copolymères à bloc PS-b-PMMA a été mise en évidence par AFM. A partir des substrats de silicium homogènes en énergie de surface, il a été possible de moduler la nanostructuration sur différents échantillons et à partir des surfaces fonctionnalisées graduellement, cette variation de nanostructuration a pu être obtenue sur un même substrat. Par l’utilisation de copolymère à bloc PS-b-PI, il est par ailleurs possible de générer des films nanostructurés sans préfonctionnalisation du substrat, sans recuit et ce quelle que soit l’épaisseur du film. Dans une troisième partie, l’influence des interactions aux interfaces sur l’assemblage capillaire/convectif dirigé de nanoparticules d’or a été démontré par microscopie à champ sombre. La nature chimique et la densité de greffage des silanes ainsi que la dimension des échantillons ont été modulées pour mettre en évidence le rôle de ces paramètres sur l’assemblage de ces particules. Cette étude montre que les interactions aux interfaces contrôlent l’assemblage des entités chimiques organiques et inorganiques et donc la nanostructuration de surface qui en résulte. / The purpose of this work is to develop a methodology based on the control of interactions at substrate/deposited material interfaces in order to achieve well-defined structures at the nanoscale (nanostructuration). In particular, silane molecules were grafted onto planar substrates to adjust the physico-chemical interactions in order to consequently control block copolymers / gold nanoparticles self-assemblies. The first part describes the experimental set-up developed to graft alkyl silanes through vapor phase strategy. The modification can be finely tuned such that homogeneously or gradually functionalized surfaces with either one or two silanes (or- or two-component substrate, respectively) are obtained. The versatility and simplicity of our process were demonstrated by wettability measurements, X-ray photoelectron spectroscopy and microscopic analysis (AFM) performed on these different surfaces. The second part points out the influence of grafting density and polarity on block copolymers self-assembly. PS-b-PMMA films were first used. With using homogeneously-modified substrates, it has been demonstrated that block copolymers self-assembly depends on substrate surface chemistry, and different cases (dewetting, wetting, parallel or perpendicular orientation of nanodomains) were achieved as a function of the grafting density of silanes on the substrate. Using gradually-modified surface, these different nanostructures were obtained on one unique sample. Moreover, by using appropriate deposition conditions with another block copolymer (PS-b-PI), well-oriented nanostructured films were obtained without pre-functionalization or annealing, regardless of film thickness. In the third part influence of surface chemistry on gold nanoparticles deposited through capillary/convective assembly is investigated and characterized by dark field microscopy. The careful selection of silane in conjunction with appropriate grafting density are adjusted in order to emphasize the impact of these parameters on the assembly process and therefore on the surface nanostructures. This study demonstrates that the control of interfacial interactions dictates the self-assembly of organic or inorganic materials deposited on a planar substrate.

This article has been published online on 21st May 2014, in Journal of Vacuum Science & Technology A: Vac (Vol.32, Issue 4): http://scitation.aip.org/content/avs/journal/jvsta/32/4/10.1116/1.4878815?aemail=author DOI: 10.1116/1.4878815 This article may be accessed via the issue's table of contents at this link: http://scitation.aip.org/content/avs/journal/jvsta/32/4?aemail=author The surface chemistry of the bis(tri-n-butylphosphane) copper(I) acetylacetonate, [(nBu3P)2Cu(acac)], and the thermal atomic layer deposition (ALD) of Cu2O using this Cu precursor as reactant and wet oxygen as co-reactant on SiO2 substrates are studied by in-situ X-ray photoelectron spectroscopy (XPS). The Cu precursor was evaporated and exposed to the substrates kept at temperatures between 22 °C and 300 °C. The measured phosphorus and carbon concentration on the substrates indicated that most of the [nBu3P] ligands were released either in the gas phase or during adsorption. No disproportionation was observed for the Cu precursor in the temperature range between 22 °C and 145 °C. However, disproportionation of the Cu precursor was observed at 200 °C, since C/Cu concentration ratio decreased and substantial amounts of metallic Cu were present on the substrate. The amount of metallic Cu increased, when the substrate was kept at 300 °C, indicating stronger disproportionation of the Cu precursor. Hence, the upper limit for the ALD of Cu2O from this precursor lies in the temperature range between 145 °C and 200 °C, as the precursor must not alter its chemical and physical state after chemisorption on the substrate. 500 ALD cycles with the probed Cu precursor and wet O2 as co reactant were carried out on SiO2 at 145 °C. After ALD, in situ XPS analysis confirmed the presence of Cu2O on the substrate. Ex-situ spectroscopic ellipsometry indicated an average film thickness of 2.5 nm of Cu2O deposited with a growth per cycle of 0.05 Å/cycle. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) investigations depicted a homogeneous, fine, and granular morphology of the Cu2O ALD film on SiO2. AFM investigations suggest that the deposited Cu2O film is continuous on the SiO2 substrate.