<p>Functional oxide-based thin films have attracted much attention owing to their broad applications in modern society. The multifunction tuning in oxide thin films is critical for obtaining enhanced properties. In this dissertation, four new nanocomposite thin film systems with highly textured growth have been fabricated by pulsed laser deposition technique. The functionalities including ferromagnetism, ferroelectricity, multiferroism, magnetoelectric coupling, low-field magnetoresistance, transmittance, optical bandgap and dielectric constants have been demonstrated. Besides, the tunability of the functionalities have been studied via different approaches.</p> <p>First, varies deposition frequencies have been used in vertically aligned nanocomposite BaTiO₃:YMnO₃ (BTO:YMO) and BaTiO₃:La_0.7Sr_0.3Mn₃(BTO:LSMO) thin films. In both systems, the strain coupling effect between the phases are affected by the density of grain boundaries. Increasing deposition frequency generates thinner columns in BTO:YMO thin films, which enhances the anisotropic ferromagnetic response in the thin films. In contrast, the columns in BTO:LSMO thin films become discontinuous as the deposition frequency increases, leading to the diminished anisotropic ferromagnetic response. Coupling with the ferroelectricity in BTO, the room temperature multiferroic properties have been obtained in these two systems.</p> <p> Second, the impact of the film composition has been demonstrated in La_0.7Ca_0.3MnO₃ (LCMO):CeO₂thin film system, which has an insulating CeO₂in ferromagnetic conducting LCMO matrix structure. As the atomic percentage of the CeO₂increases, enhanced low-field magnetoresistance and increased metal-to-insulator transition temperature are observed. The thin films also show enhanced anisotropic ferromagnetic response comparing with the pure LCMO film.</p> <p> Third, the transition metal element in Bi₃MoM_TO₉(M_T, transition metals of Mn, Fe, Co and Ni) thin films have been varied. The thin films have a multilayered structure with M_T-rich pillar-like domains embedded in Mo-rich matrix structure. The anisotropic magnetic easy axis and optical properties have been demonstrated. By the element variation, the optical bandgaps, dielectric constants as well as anisotropic ferromagnetic properties have been achieved. </p> <p> The studies in this dissertation demonstrate several examples of tuning the multifunctionalities in oxide-based nanocomposite thin films. These enhanced properties can broaden the applications of functional oxides for advanced nanoscale devices.</p><br>

As the demand for energy increases, competition for a sustainable alternative to non-renewable energy resources has resulted in the growth of the photovoltaic industry. Although most photovoltaic technologies are based on crystalline silicon, thin film technologies have been developed with the expectation of generating a comparably high-performing product with lower processing costs. These materials have demonstrated sufficiently high optoelectronic performance to enable commercialization but concerns such as material scarcity limit terawatt level power production.<div><br></div><div>In the continuous pursuit of earth abundant solar absorber materials appropriate for thin film technologies, enargite Cu3AsS4 has been identified as a promising material due to its ideal direct band gap, stability, and high absorption. Recent efforts have demonstrated this class of copper chalcogenides exhibits band gap tunability and has solution processing capabilities for potentially scalable manufacturing. Furthermore, recent first-principles calculations of enargite Cu3AsS4 have hypothesized this material may have high carrier mobility and defect-tolerant optoelectronic properties, which further support investigation into this material. <br></div><div><br></div><div>In this dissertation, a novel reactive deposition processing route has been developed which has produced dense, single-phase enargite thin films. A champion device efficiency of 0.54% was achieved following a post deposition etching procedure on these films, which demonstrates the density and observable secondary phases were not limiting to initial nanoparticle-based device performances. Together with recent modeling efforts, the non-ideal band alignment with both the back contact and diode junction is concluded to be the primary limiting factor for high efficiency devices. <br></div><div><br></div><div>As this technology contains arsenic, concerns have been raised about its potential carcinogenicity and toxicity. Similar concerns were raised during the development of cadmium telluride technology, but these concerns have been mitigated through careful life cycle analyses and identifying strategies for responsible life cycle management. Therefore, a life cycle analysis and two risk assessments have been completed on Cu3AsS4 systems. Although emissions of arsenic and its contributions to life cycle impacts are expected to be low due to the small quantity required, hot spots have been identified to reduce waste and emissions. Reduction strategies for this material system are found to be applicable to other PV systems and include minimizing molybdenum sputter waste, reusing and recycling balance of system components, and investigating low-energy processing routes on thin substrates. This work serves to establish a basis on which the potential environmental implications of this thin film technology are understood. <br></div><div><br></div><div>This dissertation will serve as a guide toward the technical and environmental development of Cu3AsS4 thin films. Having a life cycle perspective during the systematic development of a technology will enable sustainable engineering. Furthermore, the processing and characterization methods detailed herein are expected to be generally applicable to other copper chalcogenide systems. <br></div>

Indiana University-Purdue University Indianapolis (IUPUI) / The field of two-dimensional (2D) nanomaterials first began in earnest with the discovery of graphene in 2004 due to their unique shape-dependent optical, electronic, and mechanical properties. These properties arise due to their one-dimensional confinement and are further influenced by the elemental composition of the inorganic crystal lattice. There has been an intense focus on developing new compositions of 2D nanomaterials to take advantage of their intrinsic beneficial properties in a variety of applications including catalysis, energy storage and harvesting, sensing, and polymer nanocomposites. However, compared to the field of bulk materials, the influence of surface chemistry on 2D nanomaterials is still underdeveloped. 2D nanomaterials are considered an “all-surface” atomic structure with heights of a single to few layers of atoms. The synthetic methods used to produce 2D materials include bottom-up colloidal methods and top-down exfoliation related techniques. Both cases result in poorly controlled surface chemistry with many undercoordinated surface atoms and/or undesirable molecules bound to the surface. Considering the importance surfaces play in most applications (i.e., catalysis and polymer processing) it is imperative to better understand how to manipulate the surface of 2D nanomaterials to unlock their full technological potential. Through a focus of the ligand-surface atom bonding in addition to the overall ligand structure we highlight the ability to direct morphological outcomes in lead free halide perovskites, maximize optoelectronic responses in substoichiometric tungsten oxide, and alter physicochemical properties titanium carbide MXenes. The careful control of precursor materials including poly(ethylene glycol) (PEG) surface ligands during the synthesis of bismuth halide perovskites resulted in the formation of 2D quasi-Ruddlesden-Popper phase nanomaterials. Through small angle X-ray scattering (SAXS) and in conjunction with X-ray photoelectron spectroscopy (XPS) we were able to conclude that an in-situ formation of an amino functional group on our PEG-amine ligand was inserted into the perovskite crystal lattice enabling 2D morphology formation. Additionally, through UV-vis absorption and ultraviolet photoelectron spectroscopies we were able to develop a complete electronic band structure of materials containing varying halides (i.e., Cl, Br, and I). Furthermore, through the increased solubility profile of the PEG ligands we observed solvent controlled assemblies of varying mesostructures. We developed an ex-situ ligand treatment to manipulate the localized surface plasmon resonance (LSPR) response of anion vacancy doped tungsten oxide (WO3-x) nanoplatelets (NPLs). Upon ligand treatment to alter the surface passivating ligand from carboxylic acid containing myristic acid (MA) to tetradecylphosphonic acid (TDPA) we observed a >100 nm blue shift in the LSPR response. Using Fourier transform infrared (FTIR) and Raman spectroscopies in conjunction with DFT calculated Raman spectra we were able to conclude this shift was due to the formation of tridentate phosphonate bonds on the NPLs surface. Phosphonate bonding allows for an increase in surface passivation per ligand decreasing surface trapped electrons. These previously trapped electrons were then able to participate as free electrons in the LSPR response. Electron paramagnetic spectroscopy (EPR) further supported this decrease in surface traps through a decrease and shift of the EPR signal related to metal oxide surface trapped electrons. Lastly, using our knowledge of PEG ligands we were able to modify esterification chemistry to covalently attach PEG ligands to a MXene surface. The successful formation of an ester bond between a carboxylic acid containing PEG ligand and hydroxyl terminating group on the MXene surface was supported by FTIR spectroscopy and thermogravimetric analysis. The attachment of PEG resulted in a drastic change in the hydrophilicity of the MXene surface. Where MXenes were previously only processed in extremely polar solvents the PEG attachment allowed for high dispersibility in a wide range of polar and non-polar organic solvents, effectively increasing their processability. Further, this chemistry was modified to include an additional functional group on the PEG ligand to increase the valency of the post-modification MXene nanoflakes. Overall, work presented in this dissertation represents the development and application of surface chemistry to relatively new 2D nanomaterials. We believe our work significantly increases the knowledge of 2D halide perovskite formation, manipulation of LSPR active metal oxide materials, and the future processing of MXene materials.

<p>Copper (Cu) has been used as the main conductor in interconnects due to its low resistivity. However, because of its high diffusivity, diffusion barriers/liners (tantalum nitride/tantalum; TaN/Ta) must be incorporated to surround Cu wires. Otherwise, Cu ions/atoms will drift/diffuse through the inter-metal dielectric (IMD) that separates two distinct interconnects, resulting in circuit shorting and chip failures. The scaling limit of conventional Cu diffusion barriers/liners has become the bottleneck for interconnect technology, which in turn limits the IC performance. The interconnect half-pitch size will reach ~20 nm in the coming sub-5 nm technology nodes. Meanwhile, the TaN/Ta (barrier/liner) bilayer stack has to be > 4 nm to ensure acceptable liner and diffusion barrier properties. Since TaN/Ta occupy a significant portion of the interconnect cross-section and they are much more resistive than Cu, the effective conductance of an ultra-scaled interconnect will be compromised by the thick bilayer. Therefore, two dimensional (2D) layered materials have been explored as diffusion barrier alternatives owing to their atomically thin body thicknesses. However, many of the proposed 2D barriers are prepared at too high temperatures to be compatible with the back-end-of-line (BEOL) technology. In addition, as important as the diffusion barrier properties, the liner properties of 2D materials must be evaluated, which has not yet been pursued. </p> The objective of the thesis is to develop a 2D barrier/liner that overcomes the issues mentioned. Therefore, we first visit various 2D layered materials to understand their fundamental capability as barrier candidates through theoretical calculations. Among the candidates, hexagonal-boron-nitride (h-BN) and molybdenum disulfide (MoS₂) are selected for experimental studies. In addition to studying their fundamental properties to know their potential, we have also developed techniques that can realize low-temperature-grown 2D layered materials. Metal-organic chemical vapor deposition (MOCVD) is adopted for the synthesis of BEOL-compatible MoS₂. The electrical test results demonstrate the promises of integrating 2D layered materials to the state-of-the-art interconnect technology. Furthermore, by considering not only diffusion barrier properties but also liner properties, we develop another 2D layered material, tantalum sulfide (TaS_x), using plasma-enhanced chemical vapor deposition (PECVD). The TaS_x is promising in both barrier and liner aspects and is BEOL-compatible. Therefore, we believed that the conventional TaN/Ta bilayer stack can be replaced with an ultra-thin TaS_x layer to maximize the Cu volume for ultra-scaled interconnects and improve the performance. Furthermore, Since via resistance has become the bottleneck for overall interconnect performance, we study the vertical conduction of TaS_x. Both the intrinsic and extrinsic properties of this material are investigated and engineering approaches to improve the vertical conduction are also tested. Finally, we explore the possibilities of benefiting from 2D materials in other applications and propose directions for future studies.

Cette thèse est consacrée à la fabrication ascendante (bottom-up) de matériaux nanostructurés hybrides hiérarchisés à base de nanotubes de carbone alignés verticalement (VACNTs) décorés par des nanoparticules (NPs). En fonction de leur utilisation comme cathode ou anode, des nanoparticules de soufre (S) ou silicium (Si) ont été déposées. En raison de leur structure unique et de leurs propriétés électroniques, les VACNTs agissent comme une matrice de support et un excellent collecteur de courant, améliorant ainsi les voies de transport électroniques et ioniques. La nanostructuration et le contact du S avec un matériau hôte conducteur améliore sa conductivité, tandis que la nanostructuration du Si permet d'accommoder plus facilement les variations de volume pendant les réactions électrochimiques. Dans la première partie de la thèse, nous avons synthétisé des VACNTs par une méthode de dépôt chimique en phase vapeur (HF-CVD) directement sur des fines feuilles commerciales d'aluminium et de cuivre sans aucun prétraitement des substrats. Dans la deuxième partie, nous avons décoré les parois latérales des VACNTs avec différents matériaux d'électrode, dont des nanoparticules de S et de Si. Nous avons également déposé et caractérisé des nanoparticules de nickel (Ni) sur les VACNTs en tant que matériaux alternatifs pour l'électrode positive. Aucun additif conducteur ou aucun liant polymère n'a été ajouté à la composition d'électrode. La décoration des nanotubes de carbone a été effectuée par deux méthodes différentes: méthode humide par électrodéposition et méthode sèche (par dépôt physique en phase vapeur (PVD) ou par CVD). Les structures hybrides obtenues ont été testées électrochimiquement séparément dans une pile bouton contre une contre-électrode de lithium. A notre connaissance, il s'agit de la première étude de l'évaporation du soufre sur les VACNTs et de la structure résultante (appelée ici S@VACNTs). Des essais préliminaires sur les cathodes nanostructurées obtenues (S@VACNTs revêtus d'alumine ou de polyaniline) ont montré qu'il est possible d'atteindre une capacité spécifique proche de la capacité théorique du soufre. La capacité surfacique de S@VACNTs, avec une masse de S de 0.76 mg cm-2, à un régime C/20 atteint une capacité de 1.15 mAh cm-2 au premier cycle. Pour les anodes nanostructurées au silicium (Si@VACNTs), avec une masse de Si de 4.11 mg cm-2, on montre une excellente capacité surfacique de 12.6 mAh cm-2, valeur la plus élevée pour les anodes à base de silicium nanostructurées obtenues jusqu'à présent. Dans la dernière partie de la thèse, les électrodes nanostructurées fabriquées ont été assemblées afin de réaliser la batterie complète (Li2S/Si) et sa performance électrochimique a été testée. Les capacités surfaciques obtenues pour les électrodes nanostructurées de S et de Si ouvrent la voie à la réalisation d'une LIB à haute densité d'énergie, entièrement nanostructurée, et démontrent le grand potentiel du concept proposé à base d'électrodes nanostructurées hybrides hiérarchisées. / This thesis is devoted to the bottom-up fabrication of hierarchical hybrid nanostructured materials based on active vertically aligned carbon nanotubes (VACNTs) decorated with nanoparticles (NPs). Owing to their unique structure and electronic properties, VACNTs act as a support matrix and an excellent current collector, and thus enhance the electronic and ionic transport pathways. The nanostructuration and the confinement of sulfur (S) in a conductive host material improve its conductivity, while the nanostructuration of silicon (Si) accommodates better the volume change during the electrochemical reactions. In the first part of the thesis, we have synthesized VACNTs by a hot filament chemical vapor deposition (HF-CVD) method directly over aluminum and copper commercial foils without any pretreatment of the substrates. In the second part, we have decorated the sidewalls and the surface of the VACNT carpets with various LIB's active electrode materials, including S and Si NPs. We have also deposited and characterized nickel (Ni) NPs on CNTs as alternative materials for the cathode electrode. No conductive additives or any polymer binder have been added to the electrode composition. The CNTs decoration has been done systematically through two different methods: wet method by electrodeposition and dry method by physical vapor deposition (PVD). The obtained hybrid structures have been electrochemically tested separately in a coin cell against a lithium counter-electrode. Regarding the S evaporationon VACNTs, and the S@VACNTs structure, these topics are investigated for the first time to the best of our knowledge.Preliminary tests on the obtained nanostructured cathodes (S@VACNTs coated with alumina or polyaniline) have shown that it is possible to attain a specific capacity close to S theoretical storage capacity. The surface capacity of S@VACNTs, with 0.76 mg cm-2 of S, at C/20 rate reaches 1.15 mAh cm-2 at the first cycle. For the nanostructured anodes Si@VACNTs, with 4.11 mg cm-2 of Si showed an excellent surface capacity of 12.6 mAh cm-2, the highest value for nanostructured silicon anodes obtained so far. In the last part of the thesis, the fabricated nanostructured electrodes have been assembled in a full battery (Li2S/Si) and its electrochemical performances experimentally tested. The high and well-balanced surface capacities obtained for S and Si nanostructured electrodes pave the way for realization of high energy density, all-nanostructured LIBs and demonstrate the large potentialities of the proposed hierarchical hybrid nanostructures' concept.

Les électrocatalyseurs nanostructurés à base de fer, de carbone et d’azote (Fe/C/N) sont de bonnes alternatives au platine dans les piles à combustible acide. Les Fe/C/N sont synthétisés par pyrolyse laser et sont obtenus à partir de deux précurseurs de fer (FeOOH ou Fe(acac)3), de la pyridine, (avec ou sans méthilimidazole) en présence de NH3. La variation de la fraction volumique de NH3 (RNH3) est étudiée sur une large gamme. Les caractéristiques physico-chimiques des matériaux évoluent de façon monotone avec la variation de RNH3. Les analyses par XPS permettent d’identifier une phase assimilable à du nitrure de fer pour les fortes valeurs de RNH3. Les matériaux les plus actifs en éléctrochimie sont ceux contenant une phase de nitrure de fer. Ceci suggère que la présence de nitrure de fer, permet la formation de sites actifs pour la réduction de O2..L’utilisation de toluène (mélangé à de la pyridine ou à du méthylimidazole) en présence ou non de Fe(acac)3 permet d’obtenir de nouveaux matériaux Fe/C/N ou C/N. Les matériaux C/N moins actifs que ceux contenant du fer, indiquent la présence de sites actifs à base de fer. Des recuits sous Ar ou sous NH3 à 1100°C améliorent l’activité des matériaux. Elle est due à l’élimination de sites azotés inactifs et à la transformation de sites pyridiniques en sites graphitiques. Le recuit sous NH3, plus efficace que celui sous Ar, induit une augmentation de la surface spécifique (Sspé max > 1100 m²/g). Pour un même matériau recuit sous Ar ou sous NH3 la sélectivité de la réduction de O2 (n) atteint 3,70 e- contre 3,93 e- respectivement. Le plus actif d’entre eux atteint un Edép > 950mV/ENH. / Nanostructured Iron-nitrogen-carbon (Fe/N/C) electrocatalysts is a good substitute for platinum in acidic fuel cells. Laser pyrolysis synthesis allows to obtain iron nanocomposites (Fe/N/C). The reaction involves two iron precursors, FeOOH and Fe(acac)3, combined with pyridine (and possibly methylimidazole) in the presence of NH3. The effect of large range variations of NH3’s volume fraction (RNH3) in the reactions is studied. Physicochemical properties of the materials increase monotonically with RNH3. XPS analysis shows that an iron nitride phase appears when RNH3 increase, and electrochemical analysis shows that materials with this iron nitride phase are the most active ones. These results suggest that iron nitride presence triggers the formation of active sites for the oxygen reduction reaction (ORR).Finally, we synthetize new Fe/N/C, or N/C materials using toluene (mixed with pyridine or methylimidazole) in the presence or absence of Fe(acac)3. The obtained Fe/N/C materials are more active than the N/C materials which indicates that iron plays a role in the presence of active sites for the ORR. Annealing under Ar or NH3 at a temperature of 1100°C increases the activity of all the materials. This improvement is due to the suppression of inactive nitrogen sites, and the transformation of some pyridinic sites to graphitic sites. Annealing under NH3 is more effective under Ar beacuse of the increase of the specific surface area (Sspe max > 1100 m2/g). For the same material annealed under Ar versus NH3, the selectivity (n) of the ORR goes from 3.70 up to 3.93 e- respectively. The most active one reaches Edep > 950 mV/ENH.

L’utilisation de nanoparticules de polymère pour l’encapsulation de substances utilisées en médecine, en cosmétique ou en agrochimie suscite un intérêt croissant. Parmi les polymères préparés sous forme de nanoparticules, le polyuréthane présente l’avantage d’être biocompatible, biodégradable et adaptable à de nombreuses applications. L’utilisation de diisocyanates pour sa synthèse pose néanmoins un problème sanitaire et environnemental majeur. Ce travail de thèse consiste en la synthèse d’un polyuréthane sans isocyanate, le poly(hydroxy)uréthane (PHU), puis en la préparation de nanoparticules par nanoprécipitation de ce polymère. Un objectif supplémentaire est le développement de nanoparticules de PHU thermo- et pH-stimulable. Dans une première partie, un PHU modèle a été synthétisé et caractérisé. Ce polymère a été nanoprécipité en l’absence de tensioactif afin de valider la faisabilité du procédé. La seconde partie se focalise sur l’étude approfondie et l’optimisation de la nanoprécipitation du PHU modèle en présence de tensioactif. Afin de caractériser le système polymère-solvant-eau-tensioactif, la micellisation du tensioactif et les interactions polymère-solvant ont été étudiées. Un plan factoriel complet a été réalisé afin d’optimiser le procédé de nanoprécipitation utilisant le DMSO comme solvant. Les effets principaux et d’interactions de la concentration en polymère, du volume d’eau et de la concentration en tensioactif sur la taille et la distribution de taille des nanoparticules ont été déterminés. Afin de permettre l’élimination du solvant par évaporation, la nanoprécipitation du PHU a aussi été réalisée en utilisant du THF comme solvant organique. Dans une troisième partie, trois poly(hydroxy)uréthanes pH- et thermo-stimulables ont été synthétisés et caractérisés. Des nanoparticules de faible taille et distribution de taille ont ensuite été préparées par nanoprécipitation. Une fois le solvant organique éliminé par dialyse, la réponse des nanoparticules de PHUs stimulables à des variations de température et de pH a été étudiée. / The use of polymer nanoparticles for substance encapsulation generates a growing interest in medicine, cosmetics or agro-chemistry. Among the polymers used as nano-encapsulation agents, polyurethane has the advantage to be biocompatible, biodegradable and versatile. However, the use of noxious diisocyanates for polyurethane synthesis is a major drawback. This thesis project consists in synthesizing a non-isocyanate polyurethane, poly(hydroxyl)urethane (PHU), and then preparing nanoparticles by PHU nanoprecipitation. An additional objective is the development of thermos and pH-responsive PHU nanoparticles. In a first section, a model PHU was synthesized and characterized. The polymer was then nanoprecipitated in the absence of surfactant in order to ensure the feasibility of the process. The second section focused on the in-depth study and optimization of the model PHU nanoprecipitation in the presence of a surfactant. To characterize the polymer-solvent-water-surfactant system, surfactant micellization and polymer-solvent interactions were studied. A full-factorial design was performed to optimize the nanoprecipitation process using DMSO as an organic solvent. Main and interaction effects of the polymer concentration, water volume and surfactant concentration on nanoparticle size and size distribution were determined. With the aim of eliminating the organic solvent by evaporation, PHU nanoprecipitation was also carried out using THF as the organic solvent. In the third section, three pH- and thermos-responsive PHUs were synthesized and characterized. Small and monodisperse nanoparticles were then prepared by nanoprecipitation. Once the solvent eliminated, responsive PHU nanoparticles were submitted to pH and temperature changes and size variations were studied.

No description available.

<p>Since the successful exfoliation of graphene, two-dimensional (2D) materials have attracted a lot of scientific interest due to their electronic, chemical, and mechanical properties. Due their reduced dimensionality, these 2D materials exhibit superior mechanical and optoelectronic properties when compared to their bulk counterparts. Within the family of 2D materials, the ultrathin transition metal dichalcogenides (TMDs) such as Tungsten diselenide and Molybdenum disulphide have gained significant attention due to their chemical versatility and tunability. Furthermore, it is possible to leverage the distinct characteristic properties of these 2D materials, which are held together by van der Waals forces, by stacking different 2D layers on top of each other resulting in van der Waals (vdW) heterostructures. Due to the absence of feasible methods to effectively deform the crystal structures of these 2D materials and vdW heterostructures, their mechanical properties have not been thoroughly understood. The atomistic simulations can effectively capture the material behavior at the nanoscale level and help us not only not only understand the mechanical properties of these materials but also aid in the development of tailored processes to tune the material properties for the design of novel metamaterials. Using atomistic simulations, we develop the process - property relationships which can guide the direction of experimentation efforts, thereby making the process of discovering and designing new metamaterials efficient. </p><p>In this work, we have used laser shock nanostraining technique which is a scalable approach to modulate the optomechanical properties of 2D materials and vdW materials for practical semiconductor industry applications. The deformation mechanisms of 2D materials such as graphene, boron nitride (BN) and TMDs such as WSe₂ and MoS₂ are examined by employing a laser shocking process. We report studies on crystal structure deformation of multilayered WSe₂ and monolayer graphene at ultra-high strain rate using laser shock . The laser shocking process generates high pressure at GPa level, causing asymmetric 3D straining in graphene and a novel kinked-like locking structure in multilayered WSe₂. The deformation processes and related mechanical behaviors in laser shocked 2D materials are examined using atomistic simulations. Moiré heterostructures can be obtained by introducing a twist angle between these 2D layers, which can result into vdW materials with different properties, thereby adding an additional degree of freedom in the process-property design approach. We were able to successfully create a tunable stain profile in 2D materials and vdW heterostructures to modulate the local properties such as friction, and bandgap by controlling the level of laser shock, twist angle between the 2D layers and by applying appropriate laser shock pressure . We thus extend this knowledge to further explore the pathways of strain modulation using a combination of laser shocking process, moiré engineering, and strain engineering in 2D materials consisting of graphene, BN, and MoS₂ and to develop the process - property relationships in vdW materials. </p><p>In summary, this research presents a systematic understanding of the effect of laser shocking process on the van der Waals materials and demonstrates the modulation of mechanical and opto-electronic property using laser nanostraining approach. This understanding provides us with opportunities for deterministic design of 2D materials with controllable properties for semiconductor and nanoelectronics applications.</p>

Nano materials can today be found in a wide range of consumer products and the number of new products on the market is expected to inrease. In the shadow of hope for nano materilas potential in various applications, low awareness of its health and environmental risks is hiding. Furthermore, the knowledge about people´s risk perception of nano materials is limited. Parallel to the situation described above, the scholls meet the challenge of incrasing the scientific literacy. To achieve this goal, skills in argumentation in science studies has been emphasized and the concept of socio-scientific issues has been emerged. Using focus groups as a method, this study aimed first, to explore young engineering student´s risk perception of nano materials, and secont to analyze the extent to which they apply scientific konwledge to argue about nano materials. The material from the focus group interviews was analyzed with respect to both content and interaction. To analyze the content, a thematic classification of the material was made. The interactive and communicative forms were highlighted by an analysis of arguments according to the SEE-SEP-model. Seven themes were indentified from the focus group material. It was also assumed that 55 percent of the participants´arguments were based on values, 25 percent on konwledge and 20 percent on personal experiences. Despite the absence of specific knowledge, the young engineering students have the ability to conduct a complex argumentation about nano materials where they involve the paradox; new opportunities, inresolved risks. Their risk perception is not primarily based on knowledge but on emotional expressions such as fascination, hope, resignation and fear. / Nanomaterial återfinns idag i ett brett spektrum av konsumentprodukter och antalet nya produkter förväntas öka på marknaden. I skuggan av förhoppningar om nanomaterialens potential i allehanda tillämpningar döljer sig bristfälliga kunskaper om dess hälso- och miljörisker. Vidare är kunskapen om människors riskpercetion an nanometrial begränsad. Parallellt med den ovan beskrivna situationen står skolan inför utmaningen att öka den naturvetenskapliga allmänbildningen. För att uppnå målet har kompetens inom argumentation i de naturorienterande ämnene betonats och begreppet sociovetenskapliga dilemman vuxit fram. Med fokusgrupper dom metod har studien syftat dels till att undersöka unga teknikstuderandes riskperceetpion av nanomaterial, dels till att analysera i vilken utsträckning de tillämpar vetenskapliga kunskaper för att argumentera om nanomaterial. Materialet från fokusgruppsintervjuerna analyserades med avseende på både innehåll och interaktion. För att analysera innehållet gjordes en tematisk indelning av materialet. De interaktiva och kommunikativa formerna belystes genom en argumentationsanalys enligt SEE-SEP-modellen. Sju teman identifierades ur fokusgruppmaterialet. Vidare utgick 55 % av deltagarnas argument från värderingar. därefter kom kunskap med 25 % och sist personliga erfarenheter med 20 %. Trots avsaknad av specifik kunskap, har unga teknikstuderande förmågan att föra en komplex argumentation om nanomaterial där de berör pradoxen; nya möjligheter, outredda risker. Deras riskperception baseras inte främst på kunskaper utan på emotionella uttryck så som fascination, hopp,uppgivenhet och rädsla.