Ce travail de doctorat a été réalisé dans le cadre d'un accord de cotutelle international entre l'Université de Salento (L3, Italie) et l'Université de Paris 13 (LSPM, France). L'objectif principal était la fabrication de contacts ohmiques sur des surfaces de diamant pour des applications telles que les détecteurs et les dispositifs de l’électronique. Les travaux au L3 ont été consacrés à l'étude du processus de graphitisation du diamant induit par laser afin de produire des électrodes de graphite sur des diamants intrinsèques. L'étude se concentre en particulier sur le développement d’un appareil expérimental pour l’écriture laser sur diamant tant sur les aspects matériel que logiciel, et un protocole a ainsi été développé pour la fabrication de contacts graphitiques segmentés sur de larges surfaces de diamant (cm²). Des travaux approfondis de caractérisation ont démontré la transition de phase diamant-graphite et le comportement ohmique pour les contacts électriques avec une résistivité de l'ordre de 10⁻⁵ Ω.m. Des détecteurs tout-carbone ont ainsi été développés et testés avec des faisceaux électroniques et positroniques de 450 MeV. Ils permettent d’ouvrir des perspectives en tant que cible active pour de nouvelles expériences de physique des hautes énergies (PADME) dans le cadre de l’étude de la matière noire. Le travail au LSPM a été consacré au développement d'un protocole permettant d'obtenir des contacts ohmiques sur des films diamant faiblement dopé au bore et terminé oxygène, élaborés par MPACVD. Les procédés de fabrication de contacts métalliques Ti/Au sur une structure mesa ainsi que l’implantation par des ions He, ont été développés afin d'induire une couche de graphite juste en dessous de la surface de diamant. Les mesures électriques sur des diamants légèrement dopés ([B] = 4 × 10¹⁷ cm⁻³) avec seulement des contacts métalliques ou graphitiques / métalliques ont montré que la présence de la couche graphitique rend les contacts ohmiques et conduisent à une résistance spécifique de contact égale à 3.3 × 10⁻⁴ Ω.cm². / This PhD work has been carried out in international cotutelle agreement between the University of Salento (L3, Italy) and the University of Paris 13 (LSPM, France). The main aim was the manufacturing of ohmic contacts on diamond surface for detector and electronic device applications. The work at L3 was dedicated to the laser-induced diamond graphitization process in order to produce graphitic electrodes on intrinsic diamonds. An experimental set-up dedicated to the laser writing technique on diamond has been developed in both hardware and software aspects and a protocol for the manufacturing of segmented graphitic contacts on diamond surface of large scale (cm²) has been implemented. An extensive characterization work has demonstrated the diamond-graphite phase transition and an ohmic electrical behaviour for the contacts with a resistivity of the order of ≈ 10⁻⁵ Ω.m. Eventually, an all-carbon detector has been developed and tested with 450 MeV electron and positron beams proving to be a good candidate in the role of active target for a new high-energy experiment (PADME) in the framework of the dark matter. The work at LSPM has been dedicated to the development of a protocol allowing reaching ohmic contacts on lightly boron doped diamond with oxygenated surface grown by MPACVD. The fabrication of Ti/Au metallic contact above a mesa structure has relied on a He ion implantation treatment to induce a graphitic layer underneath the diamond surface. The electrical measurements on lightly doped diamonds ([B] = 4 × 10¹⁷ cm⁻³) with metal or graphite / metal contacts have shown that the graphitic layer makes ohmic the contacts leading to a specific contact resistance as low as 3.3 × 10⁻⁴ Ω.cm². / Questo dottorato di ricerca è stato svolto in convenzione di cotutela internazionale tra l’Università del Salento (L3, Italia) e l’Università di Parigi 13 (LSPM, Francia). Il principale obiettivo è stato la fabbricazione di contatti ohmici su superficie di diamante per applicazioni come rivelatori e dispositivi elettronici. Il lavoro a L3 è stato dedicato allo studio del processo di grafitizzazione del diamante indotto da laser al fine di produrre elettrodi grafitici su diamanti intrinseci. In particolare, è stato sviluppato un apparato sperimentale dedicato alla tecnica di scrittura laser su diamante sia nelle componenti hardware che software, ed è stato realizzato un protocollo per la fabbricazione di contatti grafitici segmentati su superfici di diamante di grande scala (cm²). Un ampio lavoro di caratterizzazione ha dimostrato la transizione di fase diamante-grafite e il comportamento ohmico per i contatti elettrici con una resistività dell’ordine di 10⁻⁵ Ω.m. Pertanto, un rivelatore costituito solo di carbonio è stato sviluppato e testato con fasci elettronici e positronici di 450 MeV risultando essere un buon candidato nel ruolo di bersaglio attivo per un nuovo esperimento di fisica delle alte energie (PADME) nel contesto della materia oscura. Il lavoro a LSPM è stato dedicato allo sviluppo di un protocollo che ha consentito di ottenere contatti ohmici su diamanti leggermente drogati con boro e con superficie terminata con ossigeno, cresciuti mediante MPACVD. I processi di fabbricazione di contatti metallici Ti/Au sopra una struttura mesa sono stati sviluppato così come un trattamento di impiantazione a base di ioni di He al fine di indurre uno strato grafitico appena sotto la superficie del diamante. Le misure elettriche su diamanti leggermente drogati ([B] = 4 × 10¹⁷ cm⁻³) con contatti o solo metallici o grafitici / metallici hanno dimostrato che la presenza dello strato grafitico rende i contatti ohmici e comporta una resistenza specifica di contatto pari a 3.3 × 10⁻⁴ Ω.cm².

Ce travail consiste à l’utilisation de la technique d'écriture directe par laser par absorption à un photon pour fabriquer des nanostructures polymères et métalliques en vue d’applications en photonique et en plasmonique. Il est démontré que la température du matériau est augmentée localement et temporellement grâce à une excitation locale d’un laser continu dont la longueur d’onde se situe dans la bande d’absorption du matériau. Un modèle théorique simple a été étudié pour expliquer l'effet photothermique local et temporel, qui est déterminé par le spot de focalisation du système d'écriture directe par laser. En utilisant une résine photosensible positive, il a été démontré que les structures photoniques 1D et 2D peuvent être réalisées avec une taille aussi petite que 57 nm et avec une périodicité aussi courte que 300 nm, ce qui sont beaucoup plus petites par rapport à la limite de diffraction du système optique utilisé. Les structures photoniques 3D ont également été fabriqués pour la première fois avec une photorésine positive, permettant d’envisager de nombreuses nouvelles applications. Les structures polymères fabriquées ont été démontrés très utiles pour obtenir des nanostructures plasmoniques par soit une combinaison de la méthode d’évaporation thermique d'un film d'or et le procédé lift-off, ou par une combinaison de la méthode de pulvérisation cathodique d'une couche d'or et la méthode de recuit thermique. Les nanostructures d'or fabriquées ont été caractérisées expérimentalement et leurs propriétés optiques ont été théoriquement confirmées par des calculs FDTD. En outre, il a été démontré que les nanostructures d'or, avec les tailles et formes contrôlables, peut être réalisées en une seule étape par la technique d’écriture directe par laser grâce à l'effet thermique optiquement induit. Certaines applications de ces nanostructures métalliques sont proposées et étudiés, par exemple, le capteur d'indice de réfraction, le stockage des données et l'impression couleur. / This work focuses on the investigation of direct laser writing technique for fabrication of desired nanostructures on positive photoresist and metallic materials. The photothermal and photochemical processes deriving from one-photon absorption mechanism, which occurs when materials are excited by a green continuous-wave laser, enabled a scalable and practical approach for producing nanostructures on demand. A simple heat model was proposed to explain the local and temporal thermal effect, induced by a tiny focusing spot of the direct laser writing system. Using a positive photoresist, it was demonstrated that 1D and 2D photonic structures can be realized with a feature size as small as 57 nm and with a periodicity as short as 300 nm, which are much smaller than the diffraction limit of the used optical system. 3D photonic structures were also fabricated for the first time with a positive photoresist, paving the way to numerous applications. The fabricated polymeric structures have been demonstrated as excellent templates to obtain plasmonic nanostructures by a combination of thermal evaporation of gold film and lift-off process and/or by a combination of the sputtering of a thin gold layer and thermal annealing methods. Fabricated gold nanoarrays were experimentally characterized and their optical properties were theoretically confirmed by FDTD calculations. Furthermore, it was demonstrated that any gold nanostructure, with controllable size and shape, can be realized in one-step by direct laser writing technique thanks to the optically induced thermal effect. Some applications of these metallic nanostrucures are proposed, for instance, refractive index sensor, data storage, and color printing.

O poli (p-fenilenevinileno), ou PPV, é um polímero de grande relevância tecnológica devido a suas propriedades eletroluminescentes, que têm sido exploradas em diodos emissores de luz orgânicos, displays flexíveis e outros dispositivos optoeletrônicos. Embora o PPV seja um material de importância para muitas aplicações, a sua síntese na nano/microescala não pode ser obtida através do método padrão, o qual utiliza o aquecimento de um polímero precursor poli (cloreto de xileno tetrahidrotiofenio) (PTHT). Este trabalho mostra como a microestruturação com pulsos de femtosegundo pode ser empregada para a síntese de PPV em regiões pré-determinadas, empregando três diferentes abordagens, permitindo uma nova metodologia para a fabricação precisa de microcircuitos poliméricos complexos, (i) na primeira abordagem, o processo de conversão é obtido pela irradiação de filmes de PTHT com pulsos laser ultracurtos em regiões previamente determinadas, o que leva ao controle espacial da formação de PPV em microescala, (ii) na segunda abordagem, microestruturas tridimensionais dopadas com PTHT foram fotopolimerizadas por absorção de dois fótons. A conversão de PTHT para PPV nestas microestruturas dopadas foi obtida após um tratamento térmico, (iii) na terceira abordagem, a transferência direta induzida por laser (LIFT) com pulsos de femtossegundos permite a deposição controlada de PPV com alta resolução espacial, fornecendo micropadrões 2D, preservando sua estrutura e propriedades ópticas. As estruturas foram caracterizadas por microscopia eletrônica de varredura, microscopia óptica de transmissão, microscopia de fluorescência e microscopia confocal de fluorescência. Suas propriedades ópticas foram analisadas através de sistemas de micro-fotoluminescência e micro-absorção implementadas em um microscópio invertido. Medidas de espectroscopia Raman, microscopia de força atômica e medidas elétricas também foram realizadas. Este trabalho mostra como a microestruturação com laser de fs pode ser explorada para a síntese de PPV em regiões pré-determinadas para fabricar uma variedade de microdispositivos, abrindo novos caminhos na optoeletrônica baseada em polímeros. / Poly(p-phenylenevinylene), or PPV, is a polymer of great technological relevance due to its electroluminescent properties, which have been exploited in organic light emitting diodes, flexible displays and other optoelectronic devices. Although PPV is a material of foremost importance for many applications, its synthesis at the nano/micro scale cannot be achieved through the standard method that uses heating of a precursor polymer poly(xylene tetrahydrothiophenium chloride)(PTHT). This work demonstrates the use of direct laser writing with femtosecond pulses to obtain the synthesis of PPV in pre-determined regions, by applying three different approaches, allowing the precise fabrication of complex polymeric microcircuits, (i) in the first approach the conversion process is achieved by irradiating PTHT films with ultra-short laser pulses in previously determined regions, which leads to the spatial control of PPV formation at microscale, (ii) in the second approach, three-dimensional microstructures doped with PTHT were photopolymerized by two photons absorption. The conversion of PTHT to PPV in these doped microstructures was obtained by a subsequent thermal treatment, (iii) in the third approach, laser-induced forward transfer (LIFT) with femtosecond pulses enables the controlled deposition of PPV with high spatial resolution, providing 2D micropatterns, while preserving its structure and optical properties. The structures were characterized by scanning electron, fluorescence, transmission and confocal fluorescence microscopies. Their optical properties were analyzed by micro-photoluminescence and micro-absorption setups assembled on an inverted microscope. Raman spectroscopy, electrical measurements and atomic force microscopy were also performed. This thesis shows the use of fs-laser writing methods for the synthesis of PPV in pre-determined regions, to fabricate a variety of microdevices, thus opening new avenues in polymer-based optoelectronics.

La stéréolithographie biphotonique (TPS) est une technique de microfabrication 3D basée sur la polymérisation par absorption biphotonique qui permet d’obtenir en une seule étape des structures 3D complexes avec des détails sub-100nm. Aujourd’hui, en raison des conditions spécifiques de fabrication liées à la TPS (fort flux, confinement spatial de la photoréaction,…), un des enjeux concerne le développement de matériaux fonctionnels compatibles avec ce procédé. Dans ce contexte, l’objectif de cette thèse a été de développer de nouveaux matériaux fonctionnels à base de polymères à empreintes moléculaires (MIP) pour élaborer des capteurs chimiques. Une première partie de ce travail a consisté à mettre en place différentes méthodes dédiées à la caractérisation des propriétés géométriques, chimiques et mécaniques des matériaux élaborés par TPS. Par exemple, la vibrométrie laser a été utilisée pour la première fois afin de sonder de façon non-invasive les propriétés mécaniques de microstructures réalisées par TPS. Dans un second temps, ce travail a été mis à profit pour étudier l’impact du processus de fabrication (i.e. conditions photoniques) ainsi que des paramètres physico-chimiques affectant la photoréaction (i.e. inhibition par oxygène et nature du monomère) sur les propriétés finales des matériaux. Enfin, en s’appuyant sur les résultats obtenus, des microcapteurs chimiques à base de MIP, à lecture optique ou mécanique, ont été fabriqués. Leurs propriétés de reconnaissance moléculaire, ainsi que leurs sélectivités ont été démontrées pour une molécule cible modèle (D-L-Phe). / The two-photon stereolithography (TPS) technique is a micro-nanofabrication method based on photopolymerization by two-photon absorption that allows in a single manufacturing step to obtain complex 3D structures with high-resolution details (sub-100nm). Due to the specific conditions of TPS process (intense photon flux, spatial confinement of the photoreaction…) one of the main concerns today is the development of functional materials compatible with the TPS. According to the aforementioned, the general objective of this thesis was to develop new functional materials based on molecularly imprinted polymers (MIP) to elaborate chemical microsensors. In the first step of this work, different methods were implemented to characterize the geometrical, chemical and mechanical properties of the materials synthesized by TPS. For example, laser-Doppler vibrometry was used for first time to evaluate the mechanical properties of microstructures fabricated by TPS in a non-invasive way. In the second step, the characterization methodology was used to study the impact of the manufacturing process (i.e. photonic conditions) and the physicochemical parameters that affect the photoreaction (i.e. oxygen inhibition and the nature of the monomer) and the final properties of the materials. Finally, the obtained results enabled the prototyping of chemical microsensors based on MIP. Their molecular recognition properties and their selectivity were demonstrated for the molecule (D-L-Phe) by an optical and a mechanical sensing method.

O poli (p-fenilenevinileno), ou PPV, é um polímero de grande relevância tecnológica devido a suas propriedades eletroluminescentes, que têm sido exploradas em diodos emissores de luz orgânicos, displays flexíveis e outros dispositivos optoeletrônicos. Embora o PPV seja um material de importância para muitas aplicações, a sua síntese na nano/microescala não pode ser obtida através do método padrão, o qual utiliza o aquecimento de um polímero precursor poli (cloreto de xileno tetrahidrotiofenio) (PTHT). Este trabalho mostra como a microestruturação com pulsos de femtosegundo pode ser empregada para a síntese de PPV em regiões pré-determinadas, empregando três diferentes abordagens, permitindo uma nova metodologia para a fabricação precisa de microcircuitos poliméricos complexos, (i) na primeira abordagem, o processo de conversão é obtido pela irradiação de filmes de PTHT com pulsos laser ultracurtos em regiões previamente determinadas, o que leva ao controle espacial da formação de PPV em microescala, (ii) na segunda abordagem, microestruturas tridimensionais dopadas com PTHT foram fotopolimerizadas por absorção de dois fótons. A conversão de PTHT para PPV nestas microestruturas dopadas foi obtida após um tratamento térmico, (iii) na terceira abordagem, a transferência direta induzida por laser (LIFT) com pulsos de femtossegundos permite a deposição controlada de PPV com alta resolução espacial, fornecendo micropadrões 2D, preservando sua estrutura e propriedades ópticas. As estruturas foram caracterizadas por microscopia eletrônica de varredura, microscopia óptica de transmissão, microscopia de fluorescência e microscopia confocal de fluorescência. Suas propriedades ópticas foram analisadas através de sistemas de micro-fotoluminescência e micro-absorção implementadas em um microscópio invertido. Medidas de espectroscopia Raman, microscopia de força atômica e medidas elétricas também foram realizadas. Este trabalho mostra como a microestruturação com laser de fs pode ser explorada para a síntese de PPV em regiões pré-determinadas para fabricar uma variedade de microdispositivos, abrindo novos caminhos na optoeletrônica baseada em polímeros. / Poly(p-phenylenevinylene), or PPV, is a polymer of great technological relevance due to its electroluminescent properties, which have been exploited in organic light emitting diodes, flexible displays and other optoelectronic devices. Although PPV is a material of foremost importance for many applications, its synthesis at the nano/micro scale cannot be achieved through the standard method that uses heating of a precursor polymer poly(xylene tetrahydrothiophenium chloride)(PTHT). This work demonstrates the use of direct laser writing with femtosecond pulses to obtain the synthesis of PPV in pre-determined regions, by applying three different approaches, allowing the precise fabrication of complex polymeric microcircuits, (i) in the first approach the conversion process is achieved by irradiating PTHT films with ultra-short laser pulses in previously determined regions, which leads to the spatial control of PPV formation at microscale, (ii) in the second approach, three-dimensional microstructures doped with PTHT were photopolymerized by two photons absorption. The conversion of PTHT to PPV in these doped microstructures was obtained by a subsequent thermal treatment, (iii) in the third approach, laser-induced forward transfer (LIFT) with femtosecond pulses enables the controlled deposition of PPV with high spatial resolution, providing 2D micropatterns, while preserving its structure and optical properties. The structures were characterized by scanning electron, fluorescence, transmission and confocal fluorescence microscopies. Their optical properties were analyzed by micro-photoluminescence and micro-absorption setups assembled on an inverted microscope. Raman spectroscopy, electrical measurements and atomic force microscopy were also performed. This thesis shows the use of fs-laser writing methods for the synthesis of PPV in pre-determined regions, to fabricate a variety of microdevices, thus opening new avenues in polymer-based optoelectronics.

La microfabrication 3D par laser dans les matériaux à faible bande interdite néces- sitera l’utilisation d’impulsions intenses dans l’infrarouge proche et moyen. Cette étude expérimentale se concentre sur les spécificités de la physique d’ionisation nonlinéaire dans la gamme de longueur d’onde de 1300-2200nm. Contrairement aux semiconducteurs, l’ab- sorption nonlinéaire mesurée dans les diélectriques est indépendante de la longueur d’onde révélant ainsi l’importance accrue de l’ionisation par effet tunnel avec ces longueurs d’onde. Nous étudions également les rendements et les seuils d’ionisation multiphotonique et ava- lanche dans le silicium intrinsèque et dopé N. Les résultats couplés à l’observation des ma- tériaux irradiés montrent que les propriétés intrinsèques des semiconducteurs empêchent un dépôt d’énergie suffisamment confiné pour viser directement des applications de modifica- tion locale. Ce travail illustre les possibilités de micro-usinage laser 3D dans les diélectriques et les défis de l’extension de cette technique aux semiconducteurs. / 3D laser microfabrication inside narrow gap solids like silicon will require the use of long wavelength intense pulses. This experimental study concentrates on the specificity of the nonlinear ionization physics with tightly focused femtosecond laser beams over a wa- velength range of 1300-2200nm. The measured nonlinear absorption is independent of the wavelength in dielectrics revealing the increased importance of tunnel ionization with long wavelength. This can open up an alternative to pulse shortening toward ultraprecision op- tical breakdown in dielectrics. Using n-doped silicon, we study the multiphoton-avalanche absorption yields and thresholds inside semiconductors. Also observations of the irradia- ted materials reveal that the intrinsic properties of semiconductors prevent efficient direct energy deposition in the bulk for applications. This work illustrates opportunities for 3D laser micromachining in dielectrics and challenges for its extension to semiconductors.

Nature-inspired surfaces provide an endless potential for innovations and exploitations in material science and engineering for a broad range of applications. Particularly, significant progress has been achieved in the fields of ice formation and wetting phenomena on metallic surfaces. One of the most relevant wetting states is superhydrophobicity, which is characterized by the complete repellency of water droplets upon impinging on a surface. A superhydrophobic surface can be accompanied by additional functions such as anti- icing, corrosion-resistance or self-cleaning. A particularly attractive material to implement functional surfaces is aluminum, due to its outstanding mechanical properties such as lightweight and high strength combined with an excellent electrical conductivity and affordable price. Functionalized aluminum surfaces can further increase the added value of technical aluminum products which are used in the automotive, aerospace and life science industry among others. A promising strategy to achieve multifunctionalities is by fabricating micrometer and submicrometer features on the material’s surface. Thus, surface texturing of aluminum components is an extremely relevant topic in science and engineering which affects all facets of our lives. Until now, micropatterned aluminum surfaces, that combine water- repellent, self-cleaning and icephobic properties, have not yet been completely explored. The present doctoral thesis focuses on structuring aluminum substrates to fabricate multifunctional surfaces with superhydrophobic, self-cleaning and anti-icing properties. To accomplish this goal, scanner-based direct laser writing (DLW) and two- and four-beam direct laser interference patterning (DLIP) are applied to pattern micrometer and sub- micrometer features on aluminum. They are employed separately to fabricate single-scale textures, as well as in combination in order to obtain multi-scale geometries and complex patterns. The laser texturing parameters are optimized to maximize the addressed functionalities and their influence on the microstructure are studied. In order to explain the wetting and freezing behavior of the functional surfaces, numerical heat transfer simulation models are applied. The most promising textures are then selected and tested under realistic icing conditions simulating the freezing behavior of water droplets on aircraft parts during flight. Moreover, a new method to characterize the self-cleaning efficiency of laser-patterned aluminum is developed. The textured aluminum surfaces attained a water-repellent functionality with a static water contact angle of up to 163° and a sliding angle of 12° without chemical post-processing. This functionality permitted a self-cleaning property where the DLIP and DLW+DLIP structures provided a maximum self-cleaning efficiency with remaining contamination as low as 1 %. The ice-repellent characterization at a temperature of -20°C revealed that in all investigated laser-structured surfaces the freezing time of 8 μl droplets increased up to three times compared to an unstructured reference. Moreover, it was demonstrated, that optimized surface textures led to a reduction of the ice adhesion strength by up to 90 %.:Selbstständigkeitserklärung Kurzfassung Abstract Acknowledgements Table of content List of abbreviations and symbols 1 Motivation 2 Theoretical principles and definitions 3 State of the art 4 Materials and methods 5 Results and discussion 6 Conclusions 7 Outlook Literature Curriculum vitae of the author List of publications / Von der Natur inspirierte Oberflächen bergen ein endloses Potential für Innovationen auf den Gebieten der Materialwissenschaft und demonstrieren ein breites Anwendungsfeld. Insbesondere in den Bereichen der Eisbildung und der Benetzungsphänomene auf Metalloberflächen wurde ein bedeutender Fortschritt erzielt. Einer der relevantesten Benetzungszustände ist der der Superhydrophobizität, welcher sich durch die vollständige Abweisung von Wassertropfen auszeichnet, sobald diese auf eine Oberfläche auftreffen. Eine superhydrophobe Oberfläche kann von zusätzlichen Funktionen wie Vereisungsschutz, Korrosionsbeständigkeit oder Selbstreinigung begleitet werden. Dabei ist besonders der Werkstoff Aluminium zur Realisierung funktionaler Oberflächen attraktiv, aufgrund seiner mechanischen Eigenschaften wie etwa ein geringes Gewicht und eine hohe Festigkeit bei gleichzeitig hervorragender elektrischer Leitfähigkeit ergänzt durch einen günstigen Preis. Funktionalisierte Aluminiumoberflächen können die Wertschöpfung von technischen Aluminiumprodukten deutlich erhöhen. Diese werden u.a. im Automobilsektor, in der Luft- und Raumfahrtindustrie oder im Life-Science-Bereich eingesetzt. Ein vielversprechender Ansatz zur Realisierung multifunktionaler Eigenschaften basiert auf der Herstellung von Mikrometer- und Submikrometer-Strukturen auf der Oberfläche. Daher stellt die Texturierung von Aluminiumkomponenten ein äußerst relevantes Thema in der Wissenschaft und Technik dar, da sie sämtliche Facetten unseres täglichen Lebens tangiert. Bis heute sind laser-strukturierte Aluminiumoberflächen, die wasserabweisende, selbstreinigende und eisabweisende Eigenschaften vereinen, noch nicht vollständig erforscht. Die zugrunde liegende Dissertation thematisiert die Strukturierung von Aluminiumsubstraten zur Herstellung multifunktionaler Oberflächen mit superhydrophoben, selbstreinigenden und vereisungsmindernden Eigenschaften. Dafür, werden direktes Laserschreiben (engl. Direct laser writing, DLW) sowie die direkte Laserinterferenzstrukturierung (engl. Direct laser interference patternin, DLIP) auf Aluminium angewendet. Die Verfahren werden sowohl separat zur Herstellung von einskaligen Texturen als auch in Kombination eingesetzt, um mehrskalige komplexe Muster zu fertigen. Die Strukturierungsparameter werden zur Maximierung der erwähnten Eigenschaften hin optimiert, und ihr Einfluß auf die Mikrostruktur wird untersucht. Um das Benetzungs- und Vereisungsverhalten der funktionalisierten Oberflächen zu erklären, werden numerische Simulationsmodelle eingesetzt. Die vielversprechendsten Texturen werden unter realistischen Vereisungsbedingungen getestet, welche das Gefrierverhalten von Wassertropfen auf Flugzeugbauteilen während des Fluges simulieren. Darüber hinaus wird eine neue Methode zur Charakterisierung der Selbstreinigungseffizienz von laserstrukturiertem Aluminium entwickelt und angewendet. Die texturierten Aluminiumoberflächen erhielten ohne chemische Nachbearbeitung eine wasserabweisende Funktionalität mit einem statischen Wasserkontaktwinkel von bis zu 163° und einem Gleitwinkel von 12°. Diese Funktionalität ermöglichte eine Selbstreinigungseigenschaft, bei der die DLIP- und DLW+DLIP-Strukturen die höchste Effizienz mit einer Restverunreinigung von bis zu 1 % erzielten. Die eisabweisende Charakterisierung bei einer Temperatur von -20°C offenbarte, dass bei allen untersuchten laserstrukturierten Oberflächen die Vereisungszeit von 8 μl Wassertropfen bis um das Dreifache anstieg, im Vergleich zur unstrukturierten Referenz. Darüber hinaus konnte demonstriert werden, dass optimierte Oberflächentexturen zu einer Reduzierung der Eis- Adhäsionskraft um bis zu 90 % führten.:Selbstständigkeitserklärung Kurzfassung Abstract Acknowledgements Table of content List of abbreviations and symbols 1 Motivation 2 Theoretical principles and definitions 3 State of the art 4 Materials and methods 5 Results and discussion 6 Conclusions 7 Outlook Literature Curriculum vitae of the author List of publications

The growing demand for the Internet of Things (IoT) and Artificial Intelligence (AI) need high-speed commu-nication within short-range distances. In the Back-End-Of-Line (BEOL), Single-Mode Waveguide (SMW) with micro-mirror shows the promising application as an Optical Redistribution Layer (O-RDL) connecting photonic-chip at the interposer-level. The presented study shows the potential application of the 2-Photon-Polymerization (2PP) process for fabrication of out-of-plane coupling elements (micro-mirror) for SMW using low-loss Ormocer® hybrid polymers. This fabricated micro-mirror uses as a coupling element to connect the light from RDL to chips or for inter-layer connections at Interposer level. To evaluate the processing time, structural quality, and resolution of the printed micro-mirror, two types of lenses (63x and 25x) and Ormocer® polymers (OrmoComp and OrmoCore) were used. The optimization of the process flow for the micro-mirrors for SMW applications will be described in detail.

This paper describes technology and process development for a hybrid lithography approach pairing UV-lithography for planar single mode waveguides with 2-photon-polymerization direct-laser-writing for out-of-plane coupling mirrors. Improvements to multi-layer direct patterning of OrmoCore/-Clad material system using UV-lithography are presented. Near square core cross sections are achieved. Minimum alignment accuracy at ≈ 3 μm is observed. Cut-back measurement on single mode waveguides shows attenuation of 0.64 dB cm −1 and 1.5 dB cm −1 at 1310 nm and 1550 nm respectively. Up to 2.5-times increase of shear-strength after thermal exposure up to 300 ◦ C is found using shear tests and compared for various surface treatments. Mechanical compatibility to reflow soldering is derived. An extensive study on the pattering of ORMOCER® using 2-photon-polymerization is performed. Flat 45 ◦ -micro mirrors with sub-10 μm dimensions are 3D-printed both in OrmoCore and OrmoComp. Outlook to further research on hybrid lithography integration approach is given.

This paper describes design and advances in process development for UV-lithography of planar single mode waveguides with openings for out-of-plane coupling µ-mirrors. Improvements to multi-layer direct patterning of OrmoCore/-Clad material system using UV-lithography are presented. Near square core cross sections are achieved. However, non uniformity across 4” wafer is shown due to varying proximity and UV-intensity. Openings in full stack with steep sidewalls without residual layer are patterned. Reduction in stack thickness for very small exposure doses due to inhibition even under inert atmosphere is shown. 45° -µ-mirrors are integrated in these openings to manufacture a U-link via a single mode waveguide and two adjacent micro-mirrors. Optical characterization of U-link demonstrates the feasibility of hybrid lithography approach. However, non-uniformity of core cross-section leads to cross coupling of planar waveguides. Outlook to further research on UV-lithography of multi-layer waveguide stack and alignment with µ-mirror printing is given.