One of the most endangered assemblages of species in Europe is saproxylic beetles associated with old trees. To be able to conserve these species there is a need of developing methods to survey the fauna and to evaluate the conservation value of different oak habitats, develop instruments for landscape planning and detailed knowledge of species habitat requirements. The results are based on a data set from window and pit-fall trapping of saproxylic beetles at 94 different sites spread over four regions in southern Sweden. Additionally, 48 wooden boxes with artificial wood mould, consisting mainly of oak saw dust and oak leaves and some varying additional substrates, were studied for three years at three of the sites and their vicinities. A comparison of three methods to assess species richness and composition of the saproxylic beetle fauna in standing hollow oaks showed that all trapping methods were effective in detecting species, but as they partially target different assemblages of species it is profitable to combine the methods. Window traps gave most species but wood mould sampling is the cheapest method to sample the fauna. It was possible to predict the conservation value individual oak patches with sets of indicator species of saproxylic beetles with regard to number of species or presence of conservation priority species. Indicator sets of species effectively caught with pitfall traps gave the overall best predictions. When comparing different treatment of species indata, the explanatory power of predictions was strongest for presence/absence data. Predictions of species number and an index worked well within the same regions but gave varied result for three other regions, which shows that transferability of indicators between regions may be doubtful. Species richness was greatest in stands with large, free-standing trees. Among individual trees, large girth as well as low canopy cover, increased frequency of occurrence for several species. Forest regrowth was found to be detrimental for many beetle species. An evaluation of to what extent artificial habitats, mimicking the conditions in hollow oaks, can be exploited by saproxylic beetles showed that nearly 70% of the species found in hollow oaks was found in artificial wood mould boxes. A dead hen added to the artificial wood mould gave a higher number of beetle specimens. The number of species associated with tree hollows in oak decreased with distance from sites with hollow oaks. An analysis of species assemblages at 38 sites and positions of 33 000 large/hollow oaks showed that different beetle species dependent on a single substrate, hollow oaks, responded to different scales. The total species richness responded to a scale of 859 m and the characteristic scale of response for single species varied between 52 m and 5284 m. Several species were sensitive both to smaller and larger scales. As most sites with endangered beetles living in old oaks are small and isolated, ongoing management directed to keep old oaks free standing and sun exposed and to ensure the recruitment of young oaks, and the restoration of abandoned pasture woodlands should have a high priority in nature conservation. Artificial habitats may in critical areas be created to fill gaps in old oak habitat for parts of the species assemblage. To preserve the saproxylic beetle fauna dependent on old oaks, it is important to retain and create suitable habitats both in local stands and at the landscape level, from single hectares up to hundreds of hectares depending on the species. In some landscape, creations of new oak areas in the fragmented landscape are crucial for long-term survival of sensitive species.

No description available.

The (111) surfaces of Si and Ge were studied by scanning tunneling microscopy (STM) and photoelectron spectroscopy (PES) that are complementary techniques used to obtain structural and electronic properties of surfaces. The (111) surfaces have been of great interest because of the complex reconstructions formed by annealing. Adsorption of different types of atoms on these surfaces has been widely explored by many research groups. In this thesis work, both clean and modified Si(111) and Ge(111) surfaces were extensively studied to gain information about their atomic and electronic structures. Hydrogen plays a significant role in surface science, specifically in passivating dangling bonds of semiconductor surfaces. There has been a significant number of studies performed on hydrogen exposure of the Si(111)7x7 surface. However, most studies were done after higher exposures resulting in a 1x1 surface. In this thesis work, low hydrogen exposures were employed such that the 7x7 structure was preserved. STM images revealed that the hydrogen atoms preferentially adsorb on the rest atoms at elevated temperatures. A hydrogen terminated rest atom dangling bond is no longer visible in the STM image and the surrounding adatoms become brighter. This implies that there is a charge transfer back to the adatoms. Three types of Htermination (1H, 2H and 3H) were studied in detail by analysing the line profiles of the apparent heights. There are still unresolved issues regarding the electronic structure of the Ge(111)c(2x8) surface. By combining STM, angle-resolved photoelectron spectroscopy (ARPES), and theoretical calculations, new results about the electronic structure of the clean surface have been obtained in this thesis. A more detailed experimental surface band structure showing seven surface state bands is presented. A split surface state band in the photoemission data matched a split between two types of rest atom bands in the calculated surface band structure. A highly dispersive band close to the Fermi level was identified with states below the adatom and rest atom layers and is therefore not a pure surface state. The bias dependent STM images which support the photoemission results were in agreement with simulated images generated from the calculated electronic structure of the c(2x8) surface. Many studies have been devoted to hydrogen adsorption on Si(111)7x7 but only a few have dealt with Ge(111)c(2x8). In this work, hydrogen adsorption on Ge(111)c(2x8) has been studied using STM and ARPES. The preferred adsorption site is the rest atom. As a consequence of the adsorption on the rest atom there is a reverse charge transfer to the adatoms, which makes them appear brighter in the filled-state STM images. Photoemission results showed that for the H-exposed surface, the surface states associated with the rest-atom dangling bonds decreased in intensity while a new peak appeared in the close vicinity of the Fermi level which is not present in the spectrum of the clean surface. This is a clear evidence of a semiconducting to metallic transition of the Ge(111)c(2x8) surface. A higher H exposure on the Ge(111)c(2x8) surface was also done which resulted in a 1x1 surface. The electronic structure was investigated using ARPES. Two surface states were observed that are related to the Ge-Ge backbonds and the Ge-H bonds. Sn/Ge(111) has attracted a lot of attention from the surface science community because of the interesting phase transition from the RT-(√3x√3) phase to the LT-(3x3) phase. Previously, the Sn/Ge(111)√3x√3 surface was considered to be just a simple α- phase surface on which the Sn atoms sit on the T4 sites. However, a core-level study of the RT-(√3x√3) surface showed two components in the Sn 4d core-level spectra which implies that there are two inequivalent Sn atoms. The transition was later on explained by the dynamical fluctuation model. There have been different models proposed for the Sn/Ge(111)3x3 structure such as the 2U1D, 1U2D and IDA models. In this thesis work, the surface was studied using STM. The optimum √3x√3 surface was determined by performing different sample preparations. The LT STM images of the 3x3 surface were investigated and they showed that there are different types of Sn atoms such as up and down atoms. A histogram of the apparent height distribution revealed two peaks, a sharper peak associated with the up atoms and a broader peak for the down atoms. The height distribution was used to produce simulated Sn 4d core-level spectra and the line shape was compared to that of experimental spectra.

Blood and tissue velocities are measured and analyzed in cardiac, vascular, and other applications of diagnostic ultrasound. Errors in system performance might give invalid measurements. We developed two moving string test targets and a rotating cylinder phantom (Doppler phantoms) to characterize Doppler ultrasound systems. These phantoms were initially used to measure such variables as sample volume dimensions, location of the sample volume, and the performance of the spectral analysis. Later, specific tests were designed and performed to detect errors in signal processing, causing time delays and inaccurate velocity estimation in all Doppler modes. In cardiac motion pattern even time delays as short as 30 ms may have clinical relevance. These delays can be obtained with echocardiography by using flow and tissue Doppler and M-mode techniques together with external signals (e.g., electrocardiography (ECG) and phonocardiography). If one or more of these signals are asynchronous in relation to the other signals, an incorrect definition of cardiac time intervals may occur. To determine if such time delays in signal processing are a serious problem, we tested four commercial ultrasound systems. We used the Doppler string phantom and the rotating cylinder phantom to obtain test signals. We found time delays of up to 90 ms in one system, whereas delays were mostly short in the other systems. Further, the time delays varied relative to system settings. In two-dimensional (2D) Doppler the delays were closely related to frame rate. To determine the accuracy in velocity calibration, we tested the same four ultrasound systems using the Doppler phantoms to obtain test signals for flow (PW) and tissue (T-PW) pulse Doppler and for continuous wave (CW) Doppler. The ultrasound systems were tested with settings and transducers commonly used in cardiac applications. In two systems, the observed errors were mostly close to zero, whereas one system systematically overestimated velocity by an average of 4.6%. The detected errors are mostly negliable in clinical practice but might be significant in certain cases and research applications.

Atherosclerosis is a progressive inflammatory disease that causes lipid accumulation in the arterial wall, leading to the formation of plaques. The clinical manifestations of plaque rupture—stroke and myocardial infarction—are increasing worldwide and pose an enormous economic burden for society. Atherosclerosis development reflects a complex interaction between environmental exposures and genetic predisposition. To understand this complexity, we hypothesized that a top-down approach—one in which all molecular activities that drive atherosclerosis are examined simultaneously—is necessary to highlight those that are clinically relevant. To this end, we performed whole-genome expression profiling in multiple tissues isolated from patients with coronary artery disease (CAD). In the Stockholm Atherosclerosis Gene Expression (STAGE) study, biopsies of five tissues (arterial wall with and without atherosclerotic lesions, liver, skeletal muscle and visceral fat) were isolated from 124 CAD patients undergoing coronary artery bypass grafting surgery (CABG) at the Karolinska University Hospital, Solna and carotid lesions from 39 patients undergoing carotid artery surgery at Stockholm Söder Hospital. Detailed clinical characteristics of these patients were assembled together with a total of 303 global gene expression profiles obtained with the Affymetrix GeneChip platform. In paper 1, a two-way clustering analysis of the data identified 60 tissue clusters of functionally related genes. One cluster, partly present in both visceral fat and atherosclerotic lesions, related to atherosclerosis severity as judged by coronary angiograms. Many of the genes in that cluster were also present in a carotid lesion cluster relating to intima-media thickness (IMT) in the carotid patients. The union of all three clusters relating to extent of atherosclerosis—referred to as the “A-module”—was overrepresented with genes belonging to the transendothelial migration of leukocyte (TEML) pathway. The transcription co-factor, Lim domain binding 2 (LDB2), was identified as putative regulator of the A-module and TEML pathway in validation studies including Ldb2-/- mice. In paper 2, we investigated the increased incidence of postoperative complications in CABG patients with diabetes. Using the STAGE compendium, we identified an anti-inflammatory marker, dual-specificity phosphatase 1 (DUSP1), as a novel preoperative blood marker of risk for a prolonged hospital stay after CABG. In paper 3, plaque age was determined with C14-dating in the carotid patients. Interestingly, the strongest correlation with plaque age was not the age of the patients or IMT. Rather, the strongest correlations were with plasma insulin levels and inflammatory gene expression. Taken together, the findings in this thesis show that a top-down approach using multi-tissue gene expression profiling in CAD and C14-dating of plaques can contribute to a better understanding of the molecular processes underlying atherosclerosis development and to the identification of clinically useful biomarkers.

In this work, a selection of unresolved topics regarding the electronic and atomic structures of Si and Ge surfaces, both clean ones and those modified by metal adsorbates, are addressed. The results presented have been obtained using theoretical calculations and experimental techniques such as photoelectron spectroscopy (PES), low energy electron diffraction (LEED) and scanning tunneling microscopy (STM). Si(001) surfaces with adsorbed alkali metals can function as prototype systems for studying properties of the technologically important family of metal-semiconductor interfaces. In this work, the effect of up to one monolayer (ML) of Li on the Si(001) surface is studied using a combination of experimental and theoretical techniques. Several models for the surface atomic structures have been suggested for 0.5 and 1 ML of Li in the literature. Through the combination of experiment and theory, critical differences in the surface electronic structures between the different atomic models are identified and used to determine the most likely model for a certain Li coverage. In the literature, there are reports of an electronic structure at elevated temperature, that can be probed using angle resolved PES (ARPES), on the clean Ge(001) and Si(001) surfaces. The structure is quite unusual in the sense that it appears at an energy position above the Fermi level. Using results from a combined variable temperature ARPES and LEED study, the origin of this structure is determined. Various explanations for the structure that are available in the literature are discussed. It is found that all but thermal occupation of an ordinarily empty surface state band are inconsistent with our experimental data. In a combined theoretical and experimental study, the surface core-level shifts on clean Si(001) and Ge(001) in the c(4×2) reconstruction are investigated. In the case of the Ge 3d core-level, no previous theoretical results from the c(4×2) reconstruction are available in the literature. The unique calculated Ge 3d surface core-level shifts facilitate the identification of the atomic origins of the components in the PES data. Positive assignments can be made for seven of the eight inequivalent groups of atoms in the four topmost layers in the Ge case. Furthermore, a similar, detailed, assignment of the atomic origins of the shifts on the Si surface is presented that goes beyond previously published results. At a Sn coverage of slightly more than one ML, a 2√3 × 2√3 reconstruction can be obtained on the Si(111) surface. Two aspects of this surface are explored and presented in this work. First, theoretically derived results obtained from an atomic model in the literature are tested against new ARPES and STM data. It is concluded that the model needs to be revised in order to better explain the experimental observations. The second part is focused on the abrupt and reversible transition to a molten 1×1 phase at a temperature of about 463 K. ARPES and STM results obtained slightly below and slightly above the transition temperature reveal that the surface band structure, as well as the atomic structure, changes drastically at the transition. Six surface states are resolved on the surface at low temperature. Above the transition, the photoemission spectra are, on the other hand, dominated by a single strong surface state band. It shows a dispersion similar to that of a calculated surface band associated with the Sn-Si bond on a 1×1 surface with Sn positioned above the top layer Si atoms. There has been extensive studies of the reconstructions on Si surfaces induced by adsorption of the group III metals Al, Ga and In. Recently, this has been expanded to Tl, i.e., the heaviest element in that group. Tl is different from the other elements in group III since it exhibits a peculiar behavior of the 6s2 electrons called the “inert pair effect”. This could lead to a valence state of either 1+ or 3+. In this work, core-level PES is utilized to find that, at coverages up to one ML, Tl exhibits a 1+ valence state on Si(111), in contrast to the 3+ valence state of the other group III metals. Accordingly, the surface band structure of the 1/3 ML √3 x √3 reconstruction is found to be different in the case of Tl, compared to the other group III metals. The observations of a 1+ valence state are consistent with ARPES results from the Si(001):Tl surface at one ML. There, six surface state bands are seen. Through comparisons with a calculated surface band structure, four of those can be identified. The two remaining bands are very similar to those observed on the clean Si(001) surface.

In the growing field of spintronics, development of semiconducting magnets is a high priority. Organic-based molecular magnets are attractive candidates since their properties can be tailor-made by organic chemistry. Other advantages include low weight and low temperature processing. Vanadium tetracyanoethylene, V(TCNE)x, x~2, is particularly interesting since it is one of very few semiconducting magnets with magnetic ordering above room temperature. The aim of the research presented in this thesis was to prepare and characterize thin film organic-based magnets with focus on V(TCNE)x. Photoelectron and absorption spectroscopy studies were performed leading to a more complete picture of the electronic and chemical structure of the material. Depending on the preparation method of V(TCNE)x, the material contains varying amounts of disorder which among other things makes it very air sensitive. In this thesis, a new preparation method for organic-based magnets based on physical vapor deposition is presented and the first result shows that it generates less air sensitive V(TCNE)x than previous methods reported. A new spin valve design based on V(TCNE)x was proposed where the material delivers both spin-filtering and spin-transporting functionality, making use of its fully spin-polarized transport levels. In such devices, the interface of V(TCNE)x with ferromagnetic metals is of great importance and was hence studied. As vanadium ions always are very reactive towards oxygen, substituting vanadium by a less reactive ion would be desirable from both an interface engineering and device packaging perspective. Very few alternatives exist however that orders magnetically above room temperature. In order to find out what are the key design criteria for preparing thin film semiconducting room temperature magnets, we have begun to study systems which order magnetically much below room temperature and compared them with V(TCNE)x.

QC 20100330

Research in the field of conjugated polymers (CPs) has led to the emergence of a number of interesting research areas and commercial applications, including solar cells, flexible displays, printed electronics, biosensors, e-textiles and more. Some of the advantages of organic electronics materials, as compared to their inorganic counterparts, include high elasticity, and mechanical flexibility, which allows for a natural integration of CPs into fabrics, making them ideal for e-texile. In this thesis, a novel approach for creating transistors is presented, through the construction of electrolyte gated transistors, directly embedded on functional textile fibers. Furthermore theoretical and experimental results of the integration of functional woven devices based on these transistors are shown. The realization of woven digital logic and design schemes for devices that can be placed inside living tissue, for applications such as neural communication, are demonstrated. Reducing feature sizes in organic electronics is necessity just as in conventional microelectronics, where Moore's law has been the most impressive demonstration of this over the past decades. Here the scheme of self-assembly (SA) of biomolecular/CP hybrid nano-structures is used for creating nano electronics. It is demonstrated that proteins in the form of amyloid fibrils can be coated with the highly conducting polythiophene derivative (PEDOT-S) through molecular self-assembly in water, to form conducting nanowire networks and nanodevices at molecular dimensions. In a second SA scheme, large area patterning of connected micro-nano lines and nano transistors from the conducting polymer PEDOT-S is demonstrated through assembly of these from fluids using soft lithography. Thereby the problems of large area nano patterning, and nano registration are solved for organic electronics. The construction of functional nanoscopic materials and components through molecular self-assembly has the potential to deliver totally new concepts, and may eventually allow cheap mass production of complex three dimensional nano electronic materials and devices.

Silicon Carbide (SiC) is a wide band-gap semiconductor. Similar to silicon it can be used to make electronic devices which can be employed in several applications. SiC has some unique features, such as wide band-gap, high hardness, chemical inertness, and capability to withstand high temperatures. Its high breakdown electric field, high saturated drift velocity and high thermal conductivity are some of the most important characteristics to understand why SiC has superior electrical properties compared to silicon, and make it very attractive for power devices especially at high voltages and high frequency. The gain in reduced device sizes, reduced cooling requirements, and especially in improved energy efficiency for AC/DC conversion are a very important reasons to keep working in improving the material quality. Yet several issues still limit its full employment in all its potential applications, and many more steps have thus to be done for its complete success. The core of an electric device is the epitaxial layer grown on a substrate by chemical vapor deposition (CVD). Gases containing silicon and carbon atoms, such as silane and ethylene, are often used to grow SiC, but limits in high growth rate are given by silicon cluster formation in the gas phase which is detrimental for the epitaxial layer quality. High growth rates are needed to deposit thick layers ( > 100 μm) which are required for high power devices. Chloride-based CVD, which is usually employed in the silicon epitaxial growth industry, is based on the presence of chlorinated species in the gas mixture which prevent the formation of silicon clusters, therefore resulting in very high growth rates. This chloride-based CVD process was first started to be investigated a few years ago and then only at typical growth conditions, without exploring all its full potential, such as its performance at low or high temperature growth. In addition important parameters affecting the epitaxial layer quality in terms of defect formation and electrical characteristics are the substrate orientation and its off-cut angle. Standard processes are run on substrates having an 8° off-cut angle towards a specific crystallographic direction. On lower off-cut angles, such as 4° or almost 0° (also called on-axis) which would be more economical and could resolve problems related to bipolar degradation, many typical issues should be solved or at least minimized. For 4° off-cut angle the main problem is the step-bunching resulting in high roughness of the epi surface whereas for nominally on-axis the formation of 3C inclusions is the main problem. In this thesis we discuss and present results on the use of the chloride-based CVD process in a hot-wall reactor to further explore most of the above mentioned topics. Onaxis substrates are used to grow homopolytypic epitaxial layers; detailed experiments on the gas phase composition adopting high contents of chlorine made it possible (Paper 1). Optimization of the on-axis surface preparation prior to the growth in combination with a correct choice of chlorinated precursors and growth conditions were required to reach a growth rate of 100 μm/h of 100% 4H polytype (Paper 2). Substrates with a 4° off-cut angle could be grown free from step-bunching, one of the most common morphological issue and usually detrimental for devices. Both the standard and chlorinated-process were successfully used, but at different growth rates (Paper 3). Also for this off-cut substrate a specific surface preparation and selected growth parameters made the growth possible at rates exceeding 100 μm/h (Paper 4). The benefit of the chlorinated chemistry was tested under unusual growth conditions, such as under a concentrated gas mixture (i.e. at very low carrier gas flow) tested on different off-cut substrates (Paper 5). A great advantage of chloride-based chemistry is the feasibility of growing at very low temperatures (1300 to 1400 °C compared to the 1600 °C standard temperature). At such low temperatures 4H-SiC epitaxial layers could be grown on 8° off-axis substrates (Paper 6), while high quality heteroepitaxial 3C-SiC layers were grown on on-axis 6H-SiC substrates (Paper 7). Finally, the very high growth rates achieved by the chloride-based CVD were applied in a vertical hot-wall reactor configuration, demonstrating the ability to grow very thick SiC layers at higher rates and lower temperatures than what is typically used for bulk growth (Paper 8). This work demonstrated that a new bulk growth process could be developed based on this approach. / Kiselkarbid (SiC) är en halvledare med ett stort bandgap och precis som den mycket vanliga halvledaren kisel kan SiC användas till elektroniska komponenter för många olika tillämpningar. SiC har unika materialegenskaper så som dess stora bandgap, dess höga hårdhet och motståndskraft både mot kemiskt aggressiva miljöer och höga temperaturer. Det som framförallt gör SiC så mycket bättre än kisel är främst den höga genombrottsfältstyrkan som gör att SiC klarar höga spänningar vilket är särskilt intressant för kraftkomponenter, för användning vid höga spänningar och höga frekvenser. Med elektroniska komponenter av SiC kan man, jämfört med samma komponenter av kisel, minska komponenternas storlek och kylbehov, men den huvudsakliga vinsten är en högre energieffektivitet vid AC/DC-omvandling. De minskade energiförlusterna är ett mycket starkt argument för att fortsätta att förbättra materialkvalitén på SiC. Det är materialrelaterade problem som idag håller tillbaka SiC-teknologin och ett antal problem måste lösas för att SiC ska få sitt stora genombrott. Kärnan i en elektronisk komponent är det epitaxiella skikt som har växts ovanpå ett substrat. Ordet epitaxi kommer från grekiskans epi, som betyder ovanpå, och taxis, som betyder i ordning, så ett epitaxiellt skikt har alltså odlats på ett substrat och kopierat substratets kristallstruktur. Den vanligaste tekniken för att odla epitaxiella skikt i halvledarindustrin kallas på engelska chemical vapor deposition. Någon bra svensk översättning finns inte men tekniken innebär att man deponerar ett tunt skikt via kemiska reaktioner mellan gaser. Tekniken förkortas generallt för CVD från dess engelska namn. För att odla ett epitaxiellt skikt av SiC använder man gaser med kisel och kol, så som silan (SiH4) och eten (C2H4), som späds ut kraftigt i vätgas. För att öka tillväxthastigheten i processen måste man öka mängden silan och eten i gasblandningen. Ett problem är dock att vid höga koncentrationer av kisel bildas kiseldroppar som regnar ner på substratytan och förstör det epitaxiella skiktet. Detta faktum gör att man inte kan odla epitaxiella skikt av SiC snabbare än ca 5-10 μm i timmen. För många kraftkomponenter krävs epitaxiella skikt med en tjocklek på 100 μm, eller mer och för att kunna odla sådana skikt på rimlig tid används kloridbaserad CVD. Kloridbaserad CVD är idag standard i kiselindustrin och bygger på närvaron av klorföreningar i gasblandningen. Eftersom klor binder starkare till kisel än vad kisel gör, hindrar närvaron av klor bildningen av kiseldroppar och man kan öka koncentrationen av kisel i gasblandningen och därmed öka tillväxthastigheten betydligt. Kloridbaserad CVD för kiselkarbid började på allvar undersökas för snart tio år sedan och då var fokus främst på redan välkända tillväxtförhållanden, men den fulla potentialen hos kloridbaserad CVD, så som dess effekt på låg-  eller högtemperatur tillväxt har ännu inte studerats. Inte heller har grundliga undersökningar gjorts av vad det är i processen som har betydelse för det epitaxiella skiktets elektriska egenskaper eller för bildandet av olika defekter under tillväxten. När man kapar upp en kiselkarbidkristall i tunna skivor för att kunna odla epitaxiella skikt på dem, kapar man ofta kristallen lite snett i förhållande till hur atomplanen ligger i den. Detta gör att man får en kristallyta som ser ut lite som en trappa på atomär nivå. Detta är bra eftersom atomer som ska bygga upp det epitaxiella skiktet gärna binder till ytan vid ett sådant trappsteg eftersom de där kan binda till flera atomer samtidigt. Substrat som har kapats snett på det viset kallas off-axis substrat och för 4H-polytypen av SiC kapar man vanligen substraten 8 eller 4° snett. Substrat som kapats helt parallellt med kristallplanen kallas on-axis substrat, dessa är generellt sett svåra att odla bra epitaxiella skikt på, men man får inga spillbitar när man kapar kristallen och vissa kristalldefekter i substratet tränger inte igenom till episkiktet vilket ger bättre livslängd för de elektroniska komponenterna. För att kunna odla på on-axis substrat gjordes detaljerade undersökningar av olika gasblandningar för processen och en hög klorhalt i gasblandningen möjliggjorde en process med hög tillväxthastighet på on-axis substrat (Artikel 1). Ytterligare optimering av både gaskemin och etsning av substratytan innan tillväxt gjorde att tillväxthastigheter på 100 μm i timmen kunde användas (Artikel 2). För substrat med 4° off-axis-vinkel utvecklades en process för odling av epitaxiella skikt där vanliga kristalldefekter, som är förödande för en elektrisk komponent, eliminerades och tack vare den kloridbaserade kemin kunde skikten odlas med relativt hög hastighet (Artikel 3). Även denna process utvecklades så att tillväxthastigheten överskred 100 μm i timmen (Artikel 4). Den kloridbaserade processen testades även under mera ovanliga tillväxtförhållanden, så som under väldigt lågt vätgasflöde, alltså väldigt hög koncentration av både kisel och kol i gasblandningen (Artikel 5). Den kloridbaserade kemin möjliggjorde även tillväxt vid låga temperaturer, 1300-1400 °C i stället för 1600 °C vilket är av stort intresse för vissa applikationer. Epitaxiella skikt hög kvalité av både hexagonal 4H-SiC (Artikel 6) och kubisk 3CSiC (Artikel 7) odlades vid låga temperaturer på substrat av hexagonal SiC. Slutligen användes även den kloridbaserade kemin för att odla tjocka epitaxiella skikt vid högre temperaturer, 1700-1800 °C, med en mycket hög tillväxthastighet (Artikel 8). Detta är ett första steg mot en kloridbaserad process för att odla SiC bulkkristaller som sedan kan kapas till SiC substrat. Tack vare den kloridbaserade kemin kan betydligt lägre temperaturer än standard bulkprocesser användas som har en process temperatur på ca 2100-2400 °C.