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Linköpings universitet Institutionen för fysik, kemi och biologi

Overview
Works: 2,164 works in 2,308 publications in 1 language and 2,312 library holdings
Roles: Publisher, pub, Other
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Most widely held works by Linköpings universitet
A theoretical study of charge transport in molecular crystals by Elham Mozafari( )

3 editions published between 2012 and 2013 in English and held by 3 WorldCat member libraries worldwide

The main objective of this thesis is to provide a deeper understanding of the charge transport phenomena occuring in molecular crystals. The focus is on the stability and the dynamics of the polaron as the charge carrier. To achieve this goal, a series of numerical calculations are performed using the semi-emprical "Holstien-Peierls" model. The model considers both intra- (Holstein) and inter- (Peierls) molecular interactions, in particular the electron-phonon interactions. First, the stability of the polaron in an ordered two dimensional molecular lattice with an excess charge is studied using Resilient backPropagation, RPROP, algorithm. The stability is defined by the "polaron formation energy". This formation energy is obtained for a wide range of parameter sets including both intra- and inter-molecular electron-phonon coupling strengths and their vibrational frequencies, transfer intergral and electric field. We found that the polaron formation energies lying in the range of 50-100 meV are more interesting for our studies. The second step to cover is the dynamical behaviour of the polaron. Using the stable polaron solutions acheived in the first step, an electric field is applied as an external force, pushing the charge to move. We observed that the polaron remains stable and moves with a constant velocity for only a limited range of parameter sets. Finally, the impact of disorder and temperature on the charge dynamics is considered. Adding disorder to the system will result in a more restricted parameter set space for which the polaron is dynamically stable and mobile. Temperature is included in the Newtonian equations of motion via a random force. We observed that the polaron remains localized and moves with a diffusive behaviour up to a certain temperature. If the temperature increases to values above this critical temperature, the localized polaron becomes delocalized. All this research work is coded in MATLAB software , allowing us to run the calculations, test and validate our results
Controlled growth of hexagonal GaN pyramids and InGaN QDs by Anders Lundskog( )

3 editions published in 2012 in English and held by 3 WorldCat member libraries worldwide

In paper 6, the symmetry of the GaN pyramids were intentionally broken through the introduction of elongated openings in the SiN mask (symmetric openings was used in the previous five papers). The emission polarization vectors of the subsequently grown InGaN QDs were deterministically linked to the in-plane orientation of the pyramid it was nucleated upon, implying that the QDs inhibit an inplane anisotropy directly inherited from the pyramid template. Finally, paper 7 describes a hot-wall MOCVD reactor improvement by inserting insulating pyrolytic boron-nitride (PBN) stripes in the growth chamber. By doing this, we have completely eliminated the arcing problem between different susceptor parts. As a consequence, the reactor gained run-to-run reproducibility. Growth of state of the art advanced aluminum-gallium-nitride high electron mobility transistor structures on a 100 mm wafer with electron mobility above 2000 Vs/cm2 was demonstrated by the improved process
Nucleation and stress generation in thin films deposited with a pulsed energetic deposition flux by Daniel Magnfält( )

3 editions published in 2013 in English and held by 3 WorldCat member libraries worldwide

This thesis presents fundamental mechanisms of nucleation and early growth of and stress generation in thin polycrystalline metal films deposited using pulsed energetic deposition fluxes. The effects of a pulsed deposition flux and energetic bombardment on film nucleation was investigated using in situ stress measurements and in situ ellipsometry to determine the film thickness at which the films become continuous. Ag films where deposited using high power impulse magnetron sputtering (HiPIMS) in two series - one with constant low pulse power to minimize energetic bombardment while varying the pulse frequency and one with a constant pulse frequency while varying the pulse power, resulting in different amounts of energetic bombardment and different deposition rates - to separate the effects of a pulsed deposition flux and energetic bombardment. The thickness at which the film becomes continuous was found to decrease both with increasing pulse frequency and increasing pulse power. The effects of the increased energetic bombardment and deposition rate cannot be separated due to their coupling. Adatom lifetimes and the coalescence times for islands where calculated for different coverages and island sizes and compared to the time between pulses. It was found that the time between pulses was lower than the adatom lifetimes for certain conditions; this leads to an increase in the adatom density and therefore an increase of the nucleation density resulting in smaller thicknesses for the formation of continuous film. It was also found that the coalescence time for clusters becomes longer than the time between pulses, retarding the coalescence process; this leads to formation of long lived elongated clusters also resulting in a decrease of the thickness at which the films become continuous. Energetic bombardment during growth of Mo films using HiPIMS is found to result in large compressive stresses without the commonly observed defect induced associated lattice expansion seen when depositing films using energetic bombardment. This and a correlation between the magnitude of the compressive stress and the film density allow us to conclude that the compressive stress is generated by grain boundary densification. Two mechanisms leading to grain boundary densification and thus generation of compressive stresses are proposed
Community robustness analysis : theoretical approaches to identifying keystone structures in ecological communities by Sofia Berg( Book )

2 editions published in 2013 in English and held by 3 WorldCat member libraries worldwide

A theoretical investigation of Tin+1AlCn and Mn₂GaC MAX phases : phase stability and materials properties by Andreas Thore( Book )

2 editions published in 2014 in English and held by 2 WorldCat member libraries worldwide

Room-temperature defect-engineered spin functionalities in Ga(In)NAs alloys by Yuttapoom Puttisong( Book )

2 editions published in 2014 in English and held by 2 WorldCat member libraries worldwide

Asymmetric Oligothiophenes : Chemical Evolution of Multimodal Amyloid Ligands by Leif B. G Johansson( Book )

2 editions published in 2015 in English and held by 2 WorldCat member libraries worldwide

Excitonic Effects and Energy Upconversion in Bulk and Nanostructured ZnO by Shula Chen( Book )

2 editions published between 2013 and 2014 in English and held by 2 WorldCat member libraries worldwide

Chemical Vapour Deposition of sp2 Hybridised Boron Nitride by Mikhail Chubarov( Book )

2 editions published in 2014 in English and held by 2 WorldCat member libraries worldwide

Electric fields for surface design and chemical analysis by Ulrich Christian( Book )

2 editions published in 2008 in English and held by 2 WorldCat member libraries worldwide

This thesis deals with the use of electric fields for evaluation and control of chemical systems. An electric field can result in the flow of charge across an interface between a metal and a solution, by means of chemical reactions. This interplay between electricity and chemistry, i.e. electrochemistry, is a field of crucial importance both within research and industry. Applications based on electrochemical principles encompass such diverse areas as batteries and fuel cells, pH electrodes, and the glucose monitor used by people suffering from diabetes.A major part of the present work concerns the use of static electric fields in solutions containing a non-contacted metal surface. In such a setup it is possible to control the extent of electrochemical reactions at different positions on the metal. This allows the formation and evaluation of various types of gradients on electrodes, via indirectly induced electrochemical reactions. This approach is a new and simple way of forming for instance molecular gradients on conducting surfaces. These are very advantageous in biomimetic research, because a gradient contains a huge amount of discrete combinations of for example two molecules. The basis for the technique is the use of bipolar electrochemistry. Briefly, a surface can become a bipolar electrode (an electrode that acts as both anode and cathode) when the electric field in the solution exceeds a certain threshold value, thereby inducing redox reactions at both ends. In our experiments, the driving force for these reactions will vary along the electrode surface. Since the result of an electrochemical reaction can be the deposition or removal of material from an electrode, bipolar electrochemistry can be used to create gradients of that material on a surface. In order to gain a deeper understanding of these processes, the potential and current density distributions at bipolar electrodes were investigated with different methods. Especially the use of imaging techniques was important for the visualization and analysis of the gradients. Using this knowledge, the formation of more complex gradients was facilitated, and the results were further compared to simulations based on simple conductivity models. These simulations also provided us with means to predict the behavior of new and interesting setup geometries for pattering applications.The other major part is more application driven and deals with the use of alternating electric fields for chemical analysis, a technique known as electrochemical impedance spectroscopy (EIS). In this work, EIS has been applied for the analysis of engine oils and industrial cutting fluids. Emphasis was placed on practical aspects of the measurement procedure, and on the evaluation of the results using statistical methods. It was for example shown that it was possible to simultaneously determine the amount of different contaminants in low conducting solutions. Generally, EIS is used to measure the impedance of a solution or a solid, often as a function of the frequency of the alternating electric field. The impedance of a system is closely correlated to its complex dielectric constant, and EIS can therefor be used to examine many chemical and physical processes. It is further well suited for characterizing low conducting media with little or no redox-active species. The evaluation of impedance data is often a quite complex task, which is why we have made use of statistical methods that drastically reduce the effort and quickly reveal significant intrinsic parameters
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2 editions published in 2010 in English and held by 2 WorldCat member libraries worldwide

Polypeptide functionalized gold nanoparticles for bioanalytical applications by Robert Selegård( Book )

2 editions published in 2014 in English and held by 2 WorldCat member libraries worldwide

Denna avhandling visar hur man på ett innovativt sätt kan använda ett och samma nanomaterial för att detektera och analysera flera olika typer av proteiner och för att studera deras funktion. Detta är speciellt intressant eftersom dessa strategier kan användas dels för att undersöka hur potentiella läkemedel påverkar ett proteins funktion, dels för att upptäcka sjukdomsmarkörer i ett tidigt skede och på så vis underlätta behandlingen
First-principles study of configurational disorder in icosahedral boron-rich solids by Annop Ektarawong( Book )

2 editions published in 2015 in English and held by 2 WorldCat member libraries worldwide

Design of Transition-Metal Nitride Thin Films for Thermoelectrics by Sit Kerdsongpanya( Book )

2 editions published in 2015 in English and held by 2 WorldCat member libraries worldwide

Doping of high-Al-content AlGaN grown by MOCVD by Daniel Nilsson( Book )

2 editions published in 2014 in English and held by 2 WorldCat member libraries worldwide

Vibrations in solids From first principles lattice dynamics to high temperature phase stability by Nina Shulumba( Book )

2 editions published in 2015 in English and held by 2 WorldCat member libraries worldwide

Carbon nitride and carbon fluoride thin films prepared by HiPIMS by Susann Schmidt( Book )

2 editions published in 2013 in English and held by 2 WorldCat member libraries worldwide

The present thesis focuses on carbon based thin films prepared by high power impulse magnetron sputtering (HiPIMS) and direct current magnetron sputtering (DCMS)
Effects of domestication related genes on behaviour, physiology and gene expression in chickens by Anna-Carin Karlsson( Book )

2 editions published in 2014 in English and held by 2 WorldCat member libraries worldwide

Sublimation growth and performance of cubic silicon carbide by Remigijus Vasiliauskas( Book )

2 editions published in 2012 in English and held by 2 WorldCat member libraries worldwide

The aim of this work was to develop operation conditions for fabrication of 3C-SiC crystals via understanding fundamentals of the growth process and to explore structural and electrical properties of the grown material, including its suitability for substrate applications. The physical vapor transport or sublimation process has already shown a capability to produce substantial quantities of large area and high quality hexagonal SiC substrates. In the present study a similar growth principle, but in a different geometry, namely sublimation epitaxy, was applied. Using this method very high growth rates (up to 1 mm/h) can be achieved for hexagonal polytypes while maintaining high material quality. Additionally, the growth process does not require expensive or hazardous materials, thus making the method very attractive for industrial use
SiC-FET gas sensors developed for control of the flue gas desulfurization system in power plants : experimental and modeling by Zhafira Darmastuti( Book )

2 editions published in 2014 in English and held by 2 WorldCat member libraries worldwide

 
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Alternative Names
Department of Physics and Measurement Technology, Biology and Chemistry

Department of Physics, Chemistry and Biology

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Linköpings universitet. Institutionen för fysik och mätteknik

Linköpings universitet. Institutionen för fysik och mätteknik, biologi och kemi

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English (43)