Development of silicon based electronics have revolutionized our every day life during the last three decades. Nowadays Si based devices operate close to their theoretical limits that is becoming a bottleneck for further progress. In particular, for the growing field of high frequency and high power electronics, Si cannot offer the required properties. Development of materials capable of providing high current densities, carrier mobilities and high breakdown fields is crucial for a progress in state of the art electronics. Epitaxial graphene grown on semi-insulating silicon carbide substrates has a high potential to be integrated in the current planar device technologies. High electron mobilities and sheet carrier densities make graphene extremely attractive for high frequency analog applications. One of the remaining challenges is the interaction of epitaxial graphene with the substrate. Typically, much lower free charge carrier mobilities, compared to free standing graphene, and doping, due to charge transfer from the substrate, is reported. Thus, a good understanding of the intrinsic free charge carriers properties and the factors affecting them is very important for further development of epitaxial graphene. III-group nitrides have been extensively studied and already have proven their high efficiency as light sources for short wavelengths. High carrier mobilities and breakdown electric fields were demonstrated for III-group nitrides, making them attractive for high frequency and high power applications. Currently, In-rich InGaN alloys and AlGaN/GaN high electron mobility structures are of high interest for the research community due to open fundamental questions. Electrical characterization techniques, commonly used for the determination of free charge carrier properties, require good ohmic and Schottky contacts, which in certain cases can be difficult to achieve. Access to electrical properties of buried conductive channels in multilayered structures requires modification of samples and good knowledge of the electrical properties of all electrical contact within the structure. Moreover, the use of electrical contacts to electrically characterize two-dimensional electronic materials, such as graphene, can alter their intrinsic properties. Furthermore, the determination of effective mass parameters commonly employs cyclotron resonance and Shubnikov-de Haas oscillations measurements, which require long scattering times of free charge carriers, high magnetic fields and low temperatures. The optical Hall effect is an external magnetic field induced optical anisotropy in  conductive layers due to the motion of the free charge carriers under the influence of the Lorentz force, and is equivalent to the electrical Hall effect at optical frequencies. The optical Hall effect can be measured by generalized ellipsometry and provides a powerful method for the determination of free charge carrier properties in a non-destructive and contactless manner. In principle, a single optical Hall effect measurement can provide quantitative information about free charge carrier types, concentrations, mobilities and effective mass parameters at temperatures ranging from few kelvins to room temperature and above. Further, it was demonstrated that for transparent samples, a backside cavity can be employed to enhance the optical Hall effect. Measurement of the optical Hall effect by generalized ellipsometry is an indirect technique requiring subsequent data analysis. Parameterized optical models are fitted to match experimentally measured ellipsometric data by varying physically significant parameters. Analysis of the optical response of samples, containing free charge carriers, employing optical models based on the classical Drude model, which is augmented with an external magnetic field contribution, provide access to the free charge carrier properties. The main research results of the graduate studies presented in this licentiate thesis are summarized in the five scientific papers. Paper I. Description of the custom-built terahertz frequency-domain spectroscopic ellipsometer at Linköping University. The terahertz ellipsometer capabilities are demonstrated by an accurate determination of the isotropic and anisotropic refractive indices of silicon and m-plane sapphire, respectively. Further, terahertz optical Hall effect measurements of an AlGaN/GaN high electron mobility structures were employed to extract the two-dimensional electron gas sheet density, mobility and effective mass parameters. Last, in-situ optical Hall effect measurement on epitaxial graphene in a gas cell with controllable environment, were used to study the effects of environmental doping on the mobility and carrier concentration. Paper II. Presents terahertz cavity-enhanced optical Hall measurements of the monolayer and multilayer epitaxial graphene on semi-insulating 4H-SiC (0001) substrates. The data analysis revealed p-type doping for monolayer graphene with a carrier density in the low 1012 cm−2 range and a carrier mobility of 1550 cm2/V·s. For the multilayer epitaxial graphene, n-type doping with a carrier density in the low 1013 cm−2 range, a mobility of 470 cm2/V·s and an effective mass of (0.14 ± 0.03) m0 were extracted. The measurements demonstrate that cavity-enhanced optical Hall effect measurements can be applied to study electronic properties of two-dimensional materials. Paper III. Terahertz cavity-enhanced optical Hall effect measurements are employed to study anisotropic transport in as-grown monolayer, quasi free-standing monolayer and quasi free-standing bilayer epitaxial graphene on semi-insulating 4H-SiC (0001) substrates. The data analysis revealed a strong anisotropy in the carrier mobilities of the quasi freestanding bilayer graphene. The anisotropy is demonstrated to be induced by carriers scattering at the step edges of the SiC, by showing that the mobility is higher along the step than across them. The scattering mechanism is discussed based on the results of the optical Hall effect, low-energy electron microscopy, low-energy electron diffraction and Raman measurements. Paper IV. Mid-infrared spectroscopic ellipsometry and mid-infrared optical Hall effect measurements are employed to determine the electron effective mass in an In0.33Ga0.67N epitaxial layer. The data analysis reveals slightly anisotropic effective mass and carrier mobility parameters together with the optical phonon frequencies and broadenings. Paper V. Terahertz cavity-enhanced optical Hall measurements are employed to study the free charge carrier properties in a set of AlGaN/GaN high electron mobility structures with modified interfaces. The results show that the interface structure has a significant effect on the free charge carrier mobility and that the sample with a sharp interface between an AlGaN barrier and a GaN buffer layers exhibits a record mobility of 2332±73 cm2/V·s. The determined effective mass parameters showed an increase compared to the GaN value, that is attributed the the penetration of the electron wavefunction into the AlGaN barrier layer.

In a strongly correlated material the localized electrons, typically the electrons in the 3d-orbitals, become entangled with each other through the Coulomb interaction. However, these electrons also interact with more mobile (itinerant) electrons in the s- and p-orbitals. The latter process called screening as it effectively reduces the strength of the interaction between the 3d-electrons. A less studied and often neglected effect of the screening is that it also entangles the 3d-electrons with the itinerant electrons, which is equivalent to a leakage of quantum information from the 3delectrons to the environment. This process leads to decoherence since it causes the 3d-electrons to effectively lose some of their quantum mechanical properties. But what does this mean for our understanding of strongly correlated materials and can this decoherence effect be of such magnitude that neglecting it may qualitatively affect the calculated material properties? This is the question this report tries to answer, but for a minimal impurity model consisting of an atom and a few surrounding bath orbitals. / I korrelerade atomer kan lokaliserade elektroner, som elektroner i 3d orbitaler, bli kvantmekaniskt sammanflätade med varandra genom coulomb-växelverkan. Dessa elektroner kan även växelverka med mer mobila elektroner, som elektroner i s- och p-orbitaler. Denna process kallas för skärmning eftersom den effektivt sätt reducerar styrkan på repulsionen mellan elektronerna i 3d-orbitalerna. En mindre känd och ofta ignorerad effekt från skärmningen är att elektronerna i 3d-orbitalerna blir kvantmekaniskt sammanflätade med de mobila elektronerna på ett irreversibelt sätt. Detta är ekvivalent med att information om d-elektronernas position läcker ut till omgivningen. Denna informationsläcka kallas för dekoherens eftersom den ledertill att d-elektronerna förlorar en del av sina kvantmekaniska egenskaper. Frågan blir således vad dekoherens kan ha för betydelse för starkt korrelerade materials egenskaper. Kan denna effekt vara av sådan magnitud att det ger oss en helt felaktig bild om den negligeras? Detta är vad denna rapport syftar till att svara på.

The matching of a tournament could be a tedious task, especially if there are many teams takingpart. To combat this difficult task this thesis evaluates if, by creating a method, there is a wayto automate this matching. The method proposed is based on only two parameters, shortestdistance and whether the teams have faced each other already. By being based on shortestdistance the method could not only shorten the planning time but also shorten the distance thatthe participants have to travel.To test the proposed method and validate whether it would give a sufficiently good matching itis applied to an already played Bridge tournament. The tournament was played in 2019 andincluded 365 teams and 7 rounds. This tournament was matched manually based partly ondistance and whether the teams have faced each other. Teams were split into clusters andrandomly matched each other within those. Thus, the teams did not often play against the closestteam but never a team very far away. Results are given in the form of maps for each round anda table which compares the distances for both the methods.The method was applied successfully, and each round was, as excepted, a shorter distance thanthe original matching. Thus, proving that an automatic tournament matching can be done. Thereare some improvement and alteration that can be done in the future to find a matching that morelifelike.

In this project a qutrit tripod system is studied to implement quantum gates using non-Abelian geometric phases, allowing for holonomic quantum computation which in turn results in more robust computations. First, a general foundation of the theory is presented. This includes the relevant theory of matrices in Hilbert space, as well as theory of the quantum mechanics used in the report. The method is then described in depth, showing how the pulse area is fixed. Using properties of the Hamiltonian as well as the time-evolution operator of the tripod system the computational subspace can be derived. These findings are combined to show how the computational subspace evolves in time, resulting in the unitary matrix used to form quantum gates. Using educated guesses to find the necessary parameters or utilizing iterative methods to find the parameters are the two main approaches used for constructing the considered gates. Three of the suggested quantum gates are successfully implemented through educated guesses, namely X, T and Z using an angle parametrization of the phase and amplitude of the pulses. The last desired gate is the Hadamard-gate, but the implementation of said gate required numerical approximation. The reasons as to why this is the case, are later discussed.

Artificial photosynthesis is used to harvest solar energy and store it in the form of chemical bonds. The system of interest in this study does this by splitting water into hydrogen and oxygen gas through a plasmon assisted process, collective oscillations from free electron gas. This is a renewable way to store energy that could be used as an alternative to fossil based fuel. In this study, a small part of this photo catalytic system is studied, namely the interaction between plasmonically active silver nanoparticles (Ag NPs) transferring photo-excited electrons via a linker molecule, 4-aminobenzoic acid (pABA). The pABA linker molecule transfers charge from the Ag surface to a semiconductor and a catalyst performing the water splitting. The pABA can bind in different ways onto the Ag-surface and the aim of this study is to examine which bond is strongest and which best enables charge transfer. To this purpose three systems where simulated quantum mechanically using a supercomputer. The total free energy of the systems was computed and compared. Out of the three studied binding sites, the hollow-site bond (pABA binding to three silver atoms) was found to have the lowest energy, meaningit's the strongest of the possible bonds. Additionally it was found that the band gap (the energy needed to transfer charge) for the pABA decreased when bound to the Ag-surface. The hollow-site bound pABA also had the smallest band gap, meaning it requires the least energy to transfer a charge and should therefore be the best bond fitted for the photo catalytic system. / Artificiell fotosyntes används för att absorbera solenergi och förvara den i formen av kemiska bindningar. Systemet som används i denna studie gör detta genom att splittra vatten till vätgas och syrgas genom en plasmon assisterad process. Detta är ett förnyelsebart sätt att förvara energi och kan användas som ett alternativ till fossila bränslen. I denna studie studeras en liten del utav detta fotokatalytiska system nämligen interaktionen där plasmonaktiva silvernanopartiklar (Ag NPs) överför foto-exciterade elektroner genom molekyllänken 4-aminobensoesyra (pABA). Molekyllänken pABA överför laddning från silverytan till en halvledare och en katalys som utför splittringen av vattnet. pABA kan binda på olika sätt tillen silveryta och denna studie syftar till att undersöka vilken utav bindningarna som är starkast och vilken som effektivast överför laddning. För att göra detta simulerades tre system kvantmekaniskt med hjälp av en superdator, ett system för varje sorts bindning. Den totala fria energin av systemen beräknades och jämfördes. Av de tre undersökta bindningarna hadehollow-site bindningen (pABA som binder till tre silveratomer) längst energi, vilket betyder att det är den starkaste av bindningarna. Utöver detta så visade det sig att bandgapet (energin som krävs för att överföra laddning) minskade för pABA när den var bunden till Ag-ytan. Hollow-site bundet pABA hade även minst bandgap, vilket betyder att den kräver minst energi för att överföra laddning och är därmed den mest effektiva bindningen för det fotokatalytiska systemet.

In order to understand the behaviour and function of proteins, their three dimensional structure needs to be known. Determination of macro-molecules’ structures is done using X-ray diffraction or electron microscopy, where the resulting diffraction pattern is used for molecular reconstruction. These methods are however limited by radiation damage.The aim of this work is to study radiation damage of peptides in proteins using computer simulations. Increased understanding of the atomic and molecular dynamics can contribute to an improvement of the method ofimaging biological molecules. To be able to describe the processes that take place as accurately as possible, the problem must treated quantum mechanically.Thus, the simulations are performed with molecular dynamics based on first principles. In order to capture the dynamics of the excited states of the molecule when exposed to X-rays, time-dependent density functional theory with delta self-consistent field is used. These simulations are compared to ground state simulations. The results of the thesis conclude that the excited and ground state simulations result in differences in the dynamics, which are most pronounced for lager molecules.

The department of Radiation Sciences at Umeå University has obtained an old linear accelerator, intended for educational purposes. The goal of this thesis was to find proper reinforced radiation protection in an intended bunker (a room with thick concrete walls), to ensure that the radiation outside the bunker falls within acceptable levels. The main method was with the use of Monte Carlo-simulations. To properly simulate the accelerator, knowledge of the energy distribution of emitted radiation was needed. For this, a novel method for spectra determination, using several depth dose measurements including off-axis, was developed. A method that shows promising results in finding the spectra when measurements outside the primary beam are included. The found energy spectrum was then used to simulate the accelerator in the intended bunker. The resulting dose distribution was visualized together with 3D CAD-images of the bunker, to easily see in which locations outside the bunker where the dose was high. An important finding was that some changes are required to ensure that the public does not receive too high doses of radiation on a public outdoor-area that is located above the bunker. Otherwise, the accelerator is only allowed to be run 1.8 hours per year. A workaround to this problem could be to just plant a thorn bush, covering the dangerous area of radius 3m. After such a measure has been taken, which is assumed in the following results, the focus moves to the radiation that leaks into the accelerator’s intended control room, which is located right outside the bunker’s entrance door. The results show that the accelerator is only allowed to be run for a maximum of 6.1 or 3.3 hours per year (depending on the placement of the accelerator in the room), without a specific extra reinforced radiation protection consisting mainly of lead bricks. With the specific extra protection added, the accelerator is allowed to be run 44 or 54 hours per year instead, showing a distinct improvement. However, the dose rate to the control room was still quite high, 13.7 μGy/h or 11.2 μGy/h, compared to the average dose received by someone living in Sweden, which is 0.27 μGy/h. Therefore, further measures are recommended. This is however a worst case scenario, since the leakage spectrum from the accelerator itself was simulated as having the same energy spectrum as the primarybeam at 0.1 % of the intensity, which is the maximum leakage dose according to the specifications for the accelerator. This is probably an overestimation of the intensity. Also, the energy spectra of the leakage is probably of lower energy than the primary beam in at least some directions. Implementing more knowledge of the leak spectra in future work, should therefore result in more allowed run hours for the accelerator.

Thin-film solar cell research is central to the electricity production of the near future. Photovoltaic technologies based on silicon have a significant portion of the global market and installed capacity. Thin-film solar cells are port of the emerging photovoltaic technologies that are challenging silicon for a part of the electricity production based on solar power. These thin-film technologies, such as copper indium gallium selenide (CIGS) and cadmium telluride (CdTe), are lower cost and require less energy to produce, but also require rare materials. An alternative to these technologies are thin-film solar cells based on more abundant materials. To develop these new materials at Uppsala University, combinatorial synthesis is used. This method produces a significant amount of data across different measurement methods. The data needs to be analysed and combined to gather information about the characteristics of the materials being developed. To facilitate the analysis and combination of data, a database tool was created in MATLAB. The result is a program that allows its User to combine energy-dispersive X-ray spectroscopy (EDS), Raman spectroscopy and Photoluminescence spectroscopy measurements done on solar cell absorber layers. Absorber layers are the section of solar cells where sun lighet is absorbed, and electron-hole pairs are created. The program provides multiple figures and graphs combining the different data collected, enabling the User to draw conclusions about the characteristics of the sample and its suitability as an absorber layer. The combinatorial synthesis database tool created could be user for combinatorial synthesis analysis of other material samples that are not necessarily absorber layers for thin-film solar cells. This report describes both the development of the tool and the code itself.

<p> </p><p>Control of protein immobilization at sensor surfaces is of great interest within various scientific fields, since it enables studies of specific biomolecular interactions. To achieve this, one must be able to immobilize proteins with retained native structure, while minimizing non-specific protein binding. The high affinity interaction between streptavidin (SA) and biotin is extensively used as a linker between a surface, where SA is immobilized, and the (biotinylated) molecule of interest. Self- assembled monolayers (SAMs) of poly- and oligo ethylene glycol (PEG and OEG) derivatives have been proven in literature to minimize non-specific protein binding, and biotin-exposing SAMs have been shown efficient for immobilization of SA.</p><p>The aim of this master's thesis project was to develop biotinylated gold surfaces for quartz crystal microbalance with dissipation monitoring (QCM-D) applications through the self-assembly of mixed monolayers of thiolated OEG (or PEG) derivatives with or without a terminal biotin head group. For this, different thiol compounds were to be compared and evaluated. For the systems under study, the required biotin density for maximum specific SA immobilization was to be established, while keeping the non-specific serum adsorption at a minimum. Model experiments with biotinylated proteins immobilized to the SA-functionalized surfaces were to be performed to evaluate the possibilities for commercialization.</p><p>A protocol for the preparation of a novel biotinylated surface was developed based on the immersion of gold substrates in an ethanolic incubation solution of dithiols with OEG chains (SS-OEG and SS-OEG-biotin, 99:1) and found to give reproducible results with respect to low non-specific protein binding and immobilization of a monolayer of SA. The modified surfaces allowed for subsequent immobilization of biotinylated bovine serum albumin (bBSA) and biotinylated plasminogen (bPLG). PLG was the subject of a challenging case study, using a combination of QCM-D and surface plasmon resonance (SPR), where the immobilized protein was subjected to low molecular weight ligands that were believed to induce conformational changes. The high control of the surface chemistry allowed for the interpretation of the increased dissipation shift upon ligand binding in terms of conformational changes.</p><p>An obstacle before commercialization of the described biotinylated surfaces is that they do not seem stable for storage > 7 days. The reasons for this have to be investigated further.</p>

Control of protein immobilization at sensor surfaces is of great interest within various scientific fields, since it enables studies of specific biomolecular interactions. To achieve this, one must be able to immobilize proteins with retained native structure, while minimizing non-specific protein binding. The high affinity interaction between streptavidin (SA) and biotin is extensively used as a linker between a surface, where SA is immobilized, and the (biotinylated) molecule of interest. Self- assembled monolayers (SAMs) of poly- and oligo ethylene glycol (PEG and OEG) derivatives have been proven in literature to minimize non-specific protein binding, and biotin-exposing SAMs have been shown efficient for immobilization of SA. The aim of this master's thesis project was to develop biotinylated gold surfaces for quartz crystal microbalance with dissipation monitoring (QCM-D) applications through the self-assembly of mixed monolayers of thiolated OEG (or PEG) derivatives with or without a terminal biotin head group. For this, different thiol compounds were to be compared and evaluated. For the systems under study, the required biotin density for maximum specific SA immobilization was to be established, while keeping the non-specific serum adsorption at a minimum. Model experiments with biotinylated proteins immobilized to the SA-functionalized surfaces were to be performed to evaluate the possibilities for commercialization. A protocol for the preparation of a novel biotinylated surface was developed based on the immersion of gold substrates in an ethanolic incubation solution of dithiols with OEG chains (SS-OEG and SS-OEG-biotin, 99:1) and found to give reproducible results with respect to low non-specific protein binding and immobilization of a monolayer of SA. The modified surfaces allowed for subsequent immobilization of biotinylated bovine serum albumin (bBSA) and biotinylated plasminogen (bPLG). PLG was the subject of a challenging case study, using a combination of QCM-D and surface plasmon resonance (SPR), where the immobilized protein was subjected to low molecular weight ligands that were believed to induce conformational changes. The high control of the surface chemistry allowed for the interpretation of the increased dissipation shift upon ligand binding in terms of conformational changes. An obstacle before commercialization of the described biotinylated surfaces is that they do not seem stable for storage &gt; 7 days. The reasons for this have to be investigated further.