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Mammography screening aims to reduce the number of breast cancer deaths by early detection of the disease, which is one of the leading causes of deaths for middle aged women in the western world. The risk from the x-ray radiation in mammography is relatively low but still a factor in the benefit-risk ratio of screening. The characterization and optimization of a digital mammography system is presented in this thesis. The investigated system is shown to be highly dose efficient by employing a photon counting detector in a scanning multislit geometry. A novel automatic exposure control (AEC) is proposed and validated in clinical practise. The AEC uses the leading detector edge to measure the transmission of the breast. The exposure is modulated by altering the scan velocity during the scan. A W-Al anode-filter combination is proposed. The characterization of the photon counting detector is performed using the detective quantum efficiency. The effect of the photon counting detector and the multislit geometry on the measurement method is studied in detail. It is shown that the detector has a zero-frequency DQE of over 70\% and that it is quantum limited even at very low exposures. Efficient rejection of image-degrading secondary radiation is fundamental for a dose efficient system. The efficiency of the scatter rejection techniques currently used are quantified and compared to the multislit geometry. A system performance metric with its foundation in statistical decision theory is discussed. It is argued that a photon counting multislit system can operate at approximately half the dose compared to several other digital mammography techniques. / QC 20100825

Any one organization or agency, whether for-profit or non-profit organizations that are seeking to enhance their efficiency, improve production technology, thereby achieving the goal of improving productivity, with a view to the current competitive environment. Efficiency measurement is very important, it can help decision makers understand whether the organization achieve technology progress and innovation objectives. In recent years, the government and civil organizations devote themselves to measure the change of organizational efficiency and productivity. Academia constantly research and develop various models of efficiency and productivity analysis, and application to actual cases analysis. Efficiency and productivity analysis has leapt to the mainstream of production economic studies. This empirical study adopts the census data of the classification of the Chamber of Commerce and industry of manufacturing in Taiwan, using two-stage approach to explore dynamic agglomeration externalities of 2-digit manufacturing. In the first stage, we apply dynamic network data envelopment analysis and Malmquist productivity index to calculate static efficiency and dynamic efficiency of 2-digit manufacturing. In the second stage, we apply Tobit regression analysis to verify a manufacturing geographical concentration effects on productive efficiency. We also adopt two-stage least squares methods (2SLS) to validate dynamic agglomeration externalities effects of manufacturing. Based on the results of this empical study, we propose some specific practical policy alternatives and management strategies. In the last 20 years, the strctures of Taiwan manufacturing industries have significant changes, the livelihood industry and of the sharp decline in industry, the chemical industry, electronics industry, metal machinery industry is growing fast. There is an obvous agglomeration tendency toward northern Taiwan region. In static efficiency, labour-intensive manufacturing industries tend to be diminishing return to scale rendering, while knowledge-intensive industries are rendering the increasing trend. The scale efficiency of eastern region manufacturing is very low, resulting in their productive efficiency significantly lower than the northern, central, southern regional manufacturing. In dynamic efficiency, the total factor productivity (TFP) of Taiwan manufacturing industries are rendering the growth trend, achieving the goal of innovation effect. However, the technical efficiency of manufacturing are rendering decline trend. This study found that the most important impact factor on production efficiency is the internal economies of scale. Localization economies, urbanization economies, and other static agglomeration economies external effect gradually reduce. Moreover, this study also found that Taiwan manufacturing industries have notable MAR professional dynamic external economics and notable Porter regional competitive dynamic external economic effect. Besides, Taiwan manufacturing industries has noticeable human resource dynamic external economics, but we also found low wages is beneficial to regional economic growth. We should not expand to explain Taiwan manufacturing-sweatshops. This phenomenon may be caused by high salaries, high rents, high land costs and high labor costs, these factors offset the interest of agglomeration economies. Finally, Taiwan and mainland China signed a cross-strait economic cooperation framework agreement (ECFA) in Chongqing on 29 June 2010. Taiwan manufacturing inevitably be impacted and influenced by ECFA. This is an important topic worthy of further study and discussion in the future.

In this thesis, the structural, optical, and electrical properties of wurtzite MgxZn1-xO:Al and MgxZn1-xO:Ga thin films have been investigated in dependence on Mg and dopant concentration. Among the transparent conductive oxides (TCOs), ZnO based compounds have gained renewed interest as a transparent electrode for large scale applications such as defroster windows, at panel displays, touch screens, and thin film solar cells due to low material and processing cost, non-toxicity, and suitable physical properties. In general, these applications require transparent electrodes with lowest possible resistivity of rho < 10^-3 Ohmcm and lower [1]. Recently, it has been reported that Ga and Al doped ZnO thin films can be deposited with respective resistivity of 5x10^-5 Ohmcm [2] and 3 x10^-5 Ohmcm [3] which are similar to the data obtained for other practical TCOs, i.e. the resistivity of about 4x 10^-5 Ohmcm for Sn doped In2O3 (ITO) thin films [4]. Moreover, the bandgap of ZnO can be increased by alloying with Mg offering band alignment between transparent electrode and active (or buffer) layer of the device, e.g. Cu(In,Ga)Se2 solar cells [5]. The tunable bandgap of these transparent electrodes can further increase the efficiency of the devices by avoiding energy losses in the interface region of the layers. From this point of view, this work has been aimed to investigate the doping efficiency and limits in transparent conductive (Mg,Zn)O alloys. For this purpose, the samples investigated in this work have been grown by pulsed-laser deposition (PLD) using a novel, continuous composition spread method (CCS). In general, this method allows to grow thin films with lateral composition gradient(s) [6, 7]. All MgxZn1-xO:Al and MgxZn1-xO:Ga thin films have been deposited on 2-inch in diameter glass, c- or r-plane sapphire substrates using threefold segmented PLD targets in order to grow thin films with two perpendicular, lateral composition gradients, i.e. the Mg composition is varied in one direction whereas the Al/Ga concentration is varied in a perpendicular direction [7, 8]. In order to investigate the influence of the temperature, samples grown at different substrate temperatures in the range of 25 to 600 C were investigated. The optical and electrical measurements have been carried out on (5x 5)mm^2 samples that were cut from the CCS wafers along the respective composition gradients, i.e. Mg and Al/Ga contents. Subsequently, physical properties of thin films have been analyzed for a large range of Al/Ga content between 0.5 and 7 at.%, which corresponds to doping concentrations between 2x 10^20 and 3x 10^21 cm^-3, for different Mg contents x(Mg) ranging from 0.01 to 0.1. It has been found that practically the limiting the dopant concentrations is about 2 x10^21 cm^-3. Further, the electrical data suggests, that the compensating intrinsic defect is doubly chargeable hinting to the zinc vacancy (V_Zn) as microscopic origin. Increasing the dopant concentration above 2 x10^21 cm^-3 leads to a degradation of electrical and structural properties [8]. Further, the influence of growth and annealing temperatures on structural, electrical and optical properties of the films has been studied. For that purpose, Al and Ga doped (2.5 at.% = 1x10^21 cm^-3) Mg0.05Zn0.95O thin films have been chosen from CCS samples grown at T_g = (25 - 600) C . For both doping series, the samples grown at higher temperatures exhibit better crystalline quality compared to the samples grown at lower growth temperatures. As a result, samples grown at higher temperatures reveal higher Hall mobility. For the Al-doping series, the highest free charge carrier density of n = 8.2x 10^20 cm^-3 was obtained for an Mg0.05Zn0.95O:Al thin film grown at 200 C, with corresponding Hall mobility of mu = 13.3 cm^2/Vs, a resistivity of rho = 5.7x10^-4 Ohmcm, and optical bandgap of E_g = 3.8 eV. Interestingly, the free charge carrier density of n = (5 - 8) x 10^20 cm^-3 for samples grown with T_g > 300 C is clearly higher than the value of n = 1.25 x 10^20 cm^-3 that was obtained for the high temperature grown sample, i.e. at T_g = 600 C. Furthermore, for all T_g, Al-doped films have a higher doping efficiency than the Ga-doped counterparts. In order to look deeper into the microscopic origin of this behavior, the samples were post-annealed in vacuum at 400 C. Experimental results showed that the free charge carrier density of Al-doped samples first decreased and saturated afterward with increasing annealing time. On the other hand, the free charge carrier density of the Ga-doped samples first slightly increased and saturated with increasing annealing time. For both doping series, the saturation value of n ~ 1 x 10^20 cm^-3 was very close to the data that has been observed for (i) high temperature grown samples and (ii) the solubility limit of Al in ZnO of 0.3 at.% = 1.2x 10^20 cm^-3, that has been determined by Shirouzu et al. for high temperature grown (T_g > 600 C) Al-doped ZnO [9]. Correspondingly, the optical bandgap also changed, i.e. increased (decreased) for Al- (Ga-) doping series, and approached a constant value of 3.5 0 +- 0.1 eV which is explained by generation of acceptor-like compensating defects, and the solubility limit of the dopants. From XRD data, no secondary phases were found for as-grown and post-annealed films. However, the slight improvement of crystalline quality has been observed on post-annealed samples. Further, it has been shown that the growth and annealing temperatures are important as they strongly affect the metastable state of the solid solution that samples grown at low temperature represent. The low solubility limit of the dopants, i.e. 0.3 at.% for Al in ZnO under equilibrium condition, can be increased by preparing samples by non-equilibrium growth techniques [10]. This is also consistent with experimental results of this work that Al- as well as Ga-doped metastable ZnO and (Mg,Zn)O thin films can be prepared with highest possible doping efficiency for the dopant concentration up to 2.5 at.% when growth or annealing temperatures below 400 C are used.

The production of low cost, large area display systems requires a light emitting material compatible with the standard silicon (Si) based complementary metal oxide semiconductor (CMOS) technology. The crystalline bulk Si is an indirect band semiconductor with very poor optical properties. On the other hand, hydrogenated amorphous Si (a-Si:H) based wide gap alloys exhibit strong visible photoluminescence (PL) at room temperature, owing to the release of the momentum conservation law. Still, the electroluminescence (EL) intensity from the diodes based on these alloys is weak due to the limitation of the current transport by the localized states. In the frame of this work, first, the luminescent properties of amorphous silicon nitride (a-SiNx:H) thin films grown in a plasma enhanced chemical vapor deposition (PECVD) system were analyzed with respect to the nitrogen content. Then, the doping effciency of p- and n-type hydrogenated nanocrystalline Si (nc-Si:H) films was optimized via adjusting the deposition conditions. Next, the junction quality of these doped layers was checked and further improved in a homojunction pin diode. Heterojunction pin light emitting diodes (LEDs) were fabricated with a-SiNx:H as the luminescent active layer. The EL effciency of the fresh diodes was very low, as expected. As a solution, the diodes were electro-formed under high electric field leading to nanocrystallization accompanied by a strong visible light emission from the whole diode area. The current-voltage (I-V) and EL properties of these transformed diodes were investigated in detail.

Dans de nombreux procédés industriels apparaît une étape de séparation liquide/solide qui est très souvent effectuée en combinant en série une séparation mécanique et une séparation thermique (séchage). L'intégration d'un apport thermique dans un équipement de séparation mécanique offre de nombreux avantages (investissement réduit, productivité améliorée, encombrement limité...). Par ailleurs, l'utilisation simultanée des effets mécaniques et thermiques peut conduire dans certains cas à des synergies permettant une utilisation optimisée de l'énergie. Un apport thermique par chauffage diélectrique peut être adapté à une essoreuse. L'objectif de la thèse est de concevoir et réaliser un prototype à l'échelle semi-industrielle dans le but de démontrer l'intérêt énergétique d'une telle technique. Les résultats obtenus sont : le développement et l'instrumentation complète d'un pilote d'essoreuse autorisant l'insertion des micro-ondes. La mise en évidence d'une synergie entre les phénomènes de séchage induits par un chauffage diélectrique et les effets centrifuges liés à la rotation du panier dans de cas des bobines textiles.La modélisation de différents phénomènes physiques liés à l'essorage de gâteaux de filtration, à l'évaluation de leur permittivité complexe, à la connaissance du champ électromagnétique, aux écoulements d'air utilisés pour l'extraction de la vapeur et à la détermination des transferts de masse et de chaleur. / In a lot of industrial processes, liquid/solid separation is carried out by combination of mechanical and thermal separation (drying). Thermal drying in a mechanical separation device offers a lot of advantages (lower investment, higher productivity, limited footprint. . . ). Moreover, coupling mechanical and thermal effects may lead in some cases to synergic effects allowing an optimal use of energy.Thermal input by dielectric heating may be adapted to a centrifuge. The objective of the project is to design and produce a prototype at pilot scale in order to point out the energetic interest of such a process. So, mechanical separation (centrifuge filtration, drainage) and dielectric heating have to be used simultaneously. Pilot instrumentation will allow to control key parameters of the coupled operation and the global energy consumption. Main results are : the development and the full instrumentation of a centrifuge pilot allowing implement of microwaves. The demonstration of a synergy, in the case of textile spools, between drying effects generated by dielectric heating and centrifuge effects generated by centrifuge basket rotation. The simulation of different physical phenomena linked to filtration cake drainage, dielectric constants assessment, determination of electromagnetic field, air flow used for vapor extraction and determination of heat and mass transfers.

Submitted by Luis Magno Silva de Menezes (luismagno.menezes@gmail.com) on 2012-12-18T13:51:24Z No. of bitstreams: 1 Dissertação Luis Magno versão final 10-12 biblioteca digital.pdf: 916630 bytes, checksum: 0980f501c75598d4922da46e1ec09189 (MD5) / Approved for entry into archive by ÁUREA CORRÊA DA FONSECA CORRÊA DA FONSECA (aurea.fonseca@fgv.br) on 2012-12-20T16:43:17Z (GMT) No. of bitstreams: 1 Dissertação Luis Magno versão final 10-12 biblioteca digital.pdf: 916630 bytes, checksum: 0980f501c75598d4922da46e1ec09189 (MD5) / Approved for entry into archive by Marcia Bacha (marcia.bacha@fgv.br) on 2012-12-21T12:34:58Z (GMT) No. of bitstreams: 1 Dissertação Luis Magno versão final 10-12 biblioteca digital.pdf: 916630 bytes, checksum: 0980f501c75598d4922da46e1ec09189 (MD5) / Made available in DSpace on 2012-12-21T12:35:45Z (GMT). No. of bitstreams: 1 Dissertação Luis Magno versão final 10-12 biblioteca digital.pdf: 916630 bytes, checksum: 0980f501c75598d4922da46e1ec09189 (MD5) Previous issue date: 2012-10-19 / The purpose of this research was to identify the perceptions of employees about the relationship between the shopping legislation with Embrapa Semia-Arido performance based on efficiency criteria after the implementation of the ´´Pregão´´ proclamation as a new bidding modality. It were developed bibliographical, documental, field, and to ensure the validity of the information we used a triangulation of data collection techniques of document analysis, direct observation and open-ended interviews, held with employees who work or worked in the Sector Purchasing for more than 10 years and they were ´´pregoeiros´´, and researchers from the Unit, also with over 10 years experience, who had approved projects budget with the National Treasure, with performance in previous periods and after the deployment of the ´´Pregão´´. According to the analyzed documentation and from the perspective of the employees of the sector, it was identified that after the implementation of the ´´Pregão´´; the unit has achieved savings possible of resources in hiring an average of 20% below of the baseline established in the notices documents, which could indicate efficiency. However, it became evident that the error rate in the process became much larger in relation to the proceedings conducted before the ´´pregão´´, and that although this modality is indicated as beneficial, there is the impression that is being widely used inappropriately for any hiring without an analysis of bidding modality most appropriate. In this same lineage, with regard to research reports and the opinion of the researchers, it was evident that there has been budget loss for non-delivery processes made in the end of the year, resulting in not meeting goals, steps or tasks of the experiments as well, many delays in the deliveries, and waste of resources due to poor quality acquisitions that are not useful for the research work. Finally, by way of contribution, this study showed that the current public procurement legislation directly influences the performance of Embrapa Semi-Arido, and does not meet your needs as a research institution, indicating that the institution cannot follow the same rules, standards and processes legislation of acquisitions of other public administration institutions, and it needs a new legal apparatus, which gives you more flexibility to run their projects and fulfill its institutional mission / O objetivo desta pesquisa foi identificar a percepção dos empregados sobre a relação da legislação de compras com o desempenho da Embrapa Semiárido com base no critério de eficiência após a implantação do Pregão como uma nova modalidade licitatória. Foram realizadas pesquisas bibliográfica, documental, de campo, e para assegurar a validade das informações foi utilizada uma triangulação de técnicas de coleta de dados de análise documental, observação direta e entrevistas semiabertas, realizadas com empregados que atuam ou atuaram no Setor de Compras a mais de 10 anos e que fossem pregoeiros, e pesquisadores da Unidade, também com mais de 10 anos de experiência, que tivessem projetos aprovados com orçamento do Tesouro Nacional, com execução nos períodos anteriores e após à implantação do Pregão. De acordo com a documentação analisada e na ótica dos empregados do Setor, foi identificado que após a implantação do Pregão, a unidade tem conseguido economia de recursos nas contratações em média de 20% abaixo do valor de referência estabelecido nos Editais, o que poderia indicar eficiência. Entretanto, ficou evidente que o índice de erro nos processos passou a ser muito maior em relação aos processos realizados antes do pregão, e que apesar de tal modalidade ser apontada como benéfica, tem-se a impressão de que está sendo utilizada de maneira inadequada generalizadamente para toda e qualquer contratação sem uma análise prévia da modalidade licitatória mais adequada. Nessa mesma linha, no tocante aos relatórios de pesquisa e à opinião dos pesquisadores, foi evidenciado que tem havido perdas orçamentárias por não entrega de processos feitos em fim de ano, implicando em não cumprimento de metas, etapas ou tarefas dos experimentos, bem como, muitos atrasos nas entregas, e desperdícios de recursos por conta de aquisições de má qualidade que não servem para o trabalho de pesquisa. Por fim, a título de contribuição, este estudo apontou que a legislação de compras públicas atual influencia diretamente no desempenho da Embrapa Semiárido, e não atende às suas necessidades enquanto instituição de pesquisa, indicando que a instituição não pode seguir as mesmas regras, normas e legislação dos processos de aquisições dos demais órgãos da administração pública, e precisa de um novo aparato legal, que lhe proporcione maior flexibilidade para tocar seus projetos e cumprir sua missão institucional

The EU energy efficiency directive is driving the EU member states to set ambitious goals to increase energy efficiency. Mälarenergi AB is one of the Swedish energy companies, affected by the directive, that have taken an active role in order to increase efficiency within their energy production. This study was initiated to perform energy analysis and find energy optimization measures in the systems attached to one of Mälarenergi’s CHP-units, called P5.The operating conditions of the bio fueled combined heat and power plant, P5, recently changed when the connected boiler, P4, was decided to be shut down. The two boilers shared turbine, steam, feed water, condensate and oil systems, and the operating conditions of these systems changed radically when the mass flow decreased as P4 was shut down. The changed operating conditions affects the efficiency and the performance of the plant. The changed mass flow affects the capacity demands, efficiency in components and the technical conditions of the plant.The general approach through this thesis and the used methodology is based on initial analysis of the system changes, review of the necessary functions in the system and identification of the differences between the needed functions and the existing system. Optimization potential were identified where there were large differences and as a final step, technical and economic feasibility of implementing identified optimization measures was analyzed. The results shows that feasible optimization potential is identified in removing pumps without adjustable speed drives from the system, installing adjustable speed drives to the warm condensate pumps, replacing the dilution water pumps and detaching the atomization steam tank for P4. The economic feasibility to invest in a new direct heater, better adjusted to the operating conditions of P5, is small but could be an option to Mälarenergi if the alternative production cost remains high. Without the already installed adjustable speed drives in Mälarenergi’s plant the efficiency of the operations would be much lower than what it is today and the optimization potential essentially larger. The efficiency potential in the plant increases further when the attached turbine, G4, is to be dismantled and the operating conditions changes again. More extensive simplifications and rearrangements of the system can be made to decrease the energy demand for operations with 745 MWh/year. / EU:s energieffektiviserings direktiv ställer hårda krav på företag i medlemsländerna att kartlägga och analysera energiförbrukning för att identifiera åtgärder för att öka effektivitet. Utöver detta så har Sverige ambitiösa mål om ökad energieffektivitet i samtliga sektorer. Att effektivisera energiproduktionsanläggningar för att hitta effektiviseringspotential är därför aktuellt för svenska energiproducenter. Mälarenergi är ett av de energiföretag som arbetar aktivt med att kartlägga och minska sin energiförbrukning. Studien har därför genomförts för att granska panna 5 i Västerås kraftvärmeverk, för att undersöka hur energieffektiviseringsåtgärder kan identifieras i kraftvärmeprocesser där driftförutsättningar och processer har förändrats. Panna 5 har flertalet gemensamma processer med en äldre panna i anläggningen, panna 4, vars drift har upphört och pannan ska läggas ner. Driftförhållandena i de tidigare gemensamma systemen för kondensat, matarvatten, kylning och olja har därför förändrats och massflöden i systemen minskat kraftigt. De förändrade förhållandena och massflödena påverkar kapacitetsbehovet i systemen, effektiviteten i flertalet komponenter samt de tekniska kraven som ställs på panna 5. Den största förändringen i systemet är de minskade massflödena. Flödet i kondensatsystemet har minskat från ca 100 kg/s till 45 kg/s. Samma förändring i matarvattensystemet då panna 4 kopplas bort, är från 160 kg/s till 50 kg/s. Studien visar att det finns energieffektiviseringspotential i att byta ut pumpar vars pumpdrift har påverkats kraftigt, upphöra med drift av pumpar utan frekvensstyrning, installera frekvensstyrning på pumpar där flöden varierar samt förenkla och ta bort överflödiga processer som inte nyttjas vid de nya förhållandena. Processerna kan också optimeras genom att investera i en ny direktvärmare bättre lämpad för panna 5, dock är lönsamhetskalkylen för denna svag och ytterligare bedömning krävs. Resultatet visar även att då turbinen till panna 5 är uttjänt och nedmonteras så kan processerna kring panna 5 förenklas ytterligare och optimeras så pass att 745 MWh el för drift av pannan kan sparas varje år. Generellt kan det konstaterats att även förvärmare, matarvattentank och värmeväxlare är överdimensionerade när flödet i systemet minskar, kostnads-och energibesparingen för att byta ut dessa komponenter är dock negativa, eftersom komponenterna själva inte förbrukar någon energi. Att ha för stora kapaciteter i värmeväxlare bör snarare ses som en möjlighet, att kartlägga kapacitetsbehovet underlättar dock underhållsplanering i systemet. Den generella metoden som användes i studien bygger på modellen att först kartlägga de genomförda förändringarna i systemen, fastställa funktionskraven i det nya systemet och därefter analyserna skillnaderna mellan de fastställda funktionskraven och den befintliga tekniken. Optimeringspotential kan därefter identifieras där dessa två skiljer sig till stor del. Därefter utvärderas optimeringsåtgärden genom kvantitativ analys och investeringskalkylering.

In this thesis, the structural, optical, and electrical properties of wurtzite MgxZn1-xO:Al and MgxZn1-xO:Ga thin films have been investigated in dependence on Mg and dopant concentration. Among the transparent conductive oxides (TCOs), ZnO based compounds have gained renewed interest as a transparent electrode for large scale applications such as defroster windows, at panel displays, touch screens, and thin film solar cells due to low material and processing cost, non-toxicity, and suitable physical properties. In general, these applications require transparent electrodes with lowest possible resistivity of rho < 10^-3 Ohmcm and lower [1]. Recently, it has been reported that Ga and Al doped ZnO thin films can be deposited with respective resistivity of 5x10^-5 Ohmcm [2] and 3 x10^-5 Ohmcm [3] which are similar to the data obtained for other practical TCOs, i.e. the resistivity of about 4x 10^-5 Ohmcm for Sn doped In2O3 (ITO) thin films [4]. Moreover, the bandgap of ZnO can be increased by alloying with Mg offering band alignment between transparent electrode and active (or buffer) layer of the device, e.g. Cu(In,Ga)Se2 solar cells [5]. The tunable bandgap of these transparent electrodes can further increase the efficiency of the devices by avoiding energy losses in the interface region of the layers. From this point of view, this work has been aimed to investigate the doping efficiency and limits in transparent conductive (Mg,Zn)O alloys. For this purpose, the samples investigated in this work have been grown by pulsed-laser deposition (PLD) using a novel, continuous composition spread method (CCS). In general, this method allows to grow thin films with lateral composition gradient(s) [6, 7]. All MgxZn1-xO:Al and MgxZn1-xO:Ga thin films have been deposited on 2-inch in diameter glass, c- or r-plane sapphire substrates using threefold segmented PLD targets in order to grow thin films with two perpendicular, lateral composition gradients, i.e. the Mg composition is varied in one direction whereas the Al/Ga concentration is varied in a perpendicular direction [7, 8]. In order to investigate the influence of the temperature, samples grown at different substrate temperatures in the range of 25 to 600 C were investigated. The optical and electrical measurements have been carried out on (5x 5)mm^2 samples that were cut from the CCS wafers along the respective composition gradients, i.e. Mg and Al/Ga contents. Subsequently, physical properties of thin films have been analyzed for a large range of Al/Ga content between 0.5 and 7 at.%, which corresponds to doping concentrations between 2x 10^20 and 3x 10^21 cm^-3, for different Mg contents x(Mg) ranging from 0.01 to 0.1. It has been found that practically the limiting the dopant concentrations is about 2 x10^21 cm^-3. Further, the electrical data suggests, that the compensating intrinsic defect is doubly chargeable hinting to the zinc vacancy (V_Zn) as microscopic origin. Increasing the dopant concentration above 2 x10^21 cm^-3 leads to a degradation of electrical and structural properties [8]. Further, the influence of growth and annealing temperatures on structural, electrical and optical properties of the films has been studied. For that purpose, Al and Ga doped (2.5 at.% = 1x10^21 cm^-3) Mg0.05Zn0.95O thin films have been chosen from CCS samples grown at T_g = (25 - 600) C . For both doping series, the samples grown at higher temperatures exhibit better crystalline quality compared to the samples grown at lower growth temperatures. As a result, samples grown at higher temperatures reveal higher Hall mobility. For the Al-doping series, the highest free charge carrier density of n = 8.2x 10^20 cm^-3 was obtained for an Mg0.05Zn0.95O:Al thin film grown at 200 C, with corresponding Hall mobility of mu = 13.3 cm^2/Vs, a resistivity of rho = 5.7x10^-4 Ohmcm, and optical bandgap of E_g = 3.8 eV. Interestingly, the free charge carrier density of n = (5 - 8) x 10^20 cm^-3 for samples grown with T_g > 300 C is clearly higher than the value of n = 1.25 x 10^20 cm^-3 that was obtained for the high temperature grown sample, i.e. at T_g = 600 C. Furthermore, for all T_g, Al-doped films have a higher doping efficiency than the Ga-doped counterparts. In order to look deeper into the microscopic origin of this behavior, the samples were post-annealed in vacuum at 400 C. Experimental results showed that the free charge carrier density of Al-doped samples first decreased and saturated afterward with increasing annealing time. On the other hand, the free charge carrier density of the Ga-doped samples first slightly increased and saturated with increasing annealing time. For both doping series, the saturation value of n ~ 1 x 10^20 cm^-3 was very close to the data that has been observed for (i) high temperature grown samples and (ii) the solubility limit of Al in ZnO of 0.3 at.% = 1.2x 10^20 cm^-3, that has been determined by Shirouzu et al. for high temperature grown (T_g > 600 C) Al-doped ZnO [9]. Correspondingly, the optical bandgap also changed, i.e. increased (decreased) for Al- (Ga-) doping series, and approached a constant value of 3.5 0 +- 0.1 eV which is explained by generation of acceptor-like compensating defects, and the solubility limit of the dopants. From XRD data, no secondary phases were found for as-grown and post-annealed films. However, the slight improvement of crystalline quality has been observed on post-annealed samples. Further, it has been shown that the growth and annealing temperatures are important as they strongly affect the metastable state of the solid solution that samples grown at low temperature represent. The low solubility limit of the dopants, i.e. 0.3 at.% for Al in ZnO under equilibrium condition, can be increased by preparing samples by non-equilibrium growth techniques [10]. This is also consistent with experimental results of this work that Al- as well as Ga-doped metastable ZnO and (Mg,Zn)O thin films can be prepared with highest possible doping efficiency for the dopant concentration up to 2.5 at.% when growth or annealing temperatures below 400 C are used.

I denna socialpsykologiska uppsats har jag undersökt effektiviteten inom globala virtuella team. Ämnet är relevant att studera då dagens föränderliga arbetsvillkor ställer höga krav på anställningsbarhet och globala virtuella team är ett ökande arbetssätt. Detta arbetssätt är komplext och ställer höga krav på teammedlemmar. För att undersöka detta har en kvalitativ studie genomförts och grundande teori använts som metodval. Datamaterialet samlades in genom intervjuer som grundligt analyserats och genererat följande kategorier: Frihet under ansvar, Individuellt ansvar, När en arbetsdag börjar på måndagsmorgon och slutar på fredagskväll, Kommunikation genom digitala kanaler, Anta aldrig – fråga alltid, och Kulturella utmaningar. Resultatet visar att det är ett stort individuellt ansvar att vara del av ett globalt virtuellt team. Det individuella ansvaret innefattar att självständigt planera, utföra och redovisa ett resultat, att hålla tät kommunikation med sitt team, att hantera språkliga och kulturella barriärer, samarbeta med kunder som är globalt utspridda, samt att ansvara för att teknisk utrustning fungerar. Allt detta sker digitalt och i sociala avskildhet från sitt team. Detta individuella ansvar kan likställas med att driva ett eget företag. Nyckelord: Grundande teori, globalt virtuellt team, effektivitet, individuellt ansvar, frihet under ansvar / Abstract This social psychology paper aims to clarify the effectiveness of global virtual teams. The subject is relevant for study as todays ever changing work requirements raises the bar for employability and global virtual teams is growing way of working. This work force requirement is complex and sets a high standard on the team members. The results are based on a qualitative study with grounded theory as the method of choice. The data collection was made through interviews that were thoroughly analyzed and yielded the following categories: Freedom with responsibility, Individual responsibility, The workday starts on Monday morning and ends on Friday evening, Communication through digital channels, never assume – always ask, and cultural challenges. The overarching results show that there is a large individual responsibility required to be part of a global virtual team. The individual responsibility entails independent planning, execute, and render results, keep constant communication with the team, navigate language and cultural barriers, engage with a global customer base, and take responsibility that the technical equipment is functional. All of this happens digitally and in social seclusion from the team. The individual responsibility can be compared to that of running your own business. Key words: Grounding theory, global virtual team, efficiency, individual reasonability, freedom with responsibility