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- Doyle, James P.
(författare)
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Copper germanide schottky contacts to silicon and electrically active defects in n-type 6H-SiC and 4H-SiC epitaxial layers
- 1997
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Metallization for contacts to silicon devices presents amajor challenge as the linewidths are further reduced into thesub-micron regime. Copper germanide due to its relatively lowroom temperature resistivity ( ~ 10 µΩ - cm) has beenexamined as a potential contact metallixation. In addition, dueto the growing interest in silicon carbide as a potentialwide-bandgap semiconductor candidate for high voltage, power,and frequency devices, a characterization of electricallyactive deep levels was conducted on as-grown and electron andion irradiated layers as such defects can influence theelectrical behaviour of active devices. N-type 6H- and 4H-SiChave been characterized by deep level transient spectroscopy(DLTS) in conjunction with MeV electron beam irradiation andkeV hydrogen and deuterium implantation. Intrinsic levels havebeen identified in both polytypes through an examination ofas-grown and irradiated samples.It is demonstrated that silicon outdiffusion into the coppergermanide contact causes an increase in the electricalresistivity. Additionally, deviation from ideal behaviour isobserved in current-voltage (IV) measurements an indicationthat this outdiffusion of silicon produces recombinationcenters primarily in the upper part of the bandgap near to thecontact-semiconductor interface. Additionally, copper germanideis found to be morphologically unstable during theamorphous-to-crystalline transformation. The high diffusivityof copper in amorphous germanium at temperatures as low as 200°C coupled with the independence of the barrier height onthe germanium fraction used during contact formation indicatesthat the interface between copper germanide and silicon issimilar to that of copper silicide and silicon.A number of electrically active deep levels have beencharacterized in both the 4H- and 6H-SiC polytypes. In 6H-SIC,many of the defects are found to be intrinsic as they areobserved to grow as a function of increasing irradiation dose.In contrast, as-grown 4H-SiC epitaxial layers, exhibit only asingle acceptor-like level at 0.70 eV below the conduction bandedge (Ec). After irradiation the level is not observed toincrease in concentration, but two new levels are found. Theselevels are found to be unstable at room temperature in contrastto the 6H-SiC defects. In 6H-SiC, the defect concentration isfound to limit the average carrier lifetime. Through the use ofthermal annealing, SIMS, and electron irradiation, a model oftheir Origin is proposed.Keywords:Deep level transient spectroscopy (DLTS),secondary ion mass spectrometry (SIMS), amorphous germanium,electron irradiation, ion irradiation, wide-bandgap
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| 2. |
- Grimfjärd, Per, 1975-
(författare)
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Invasive treatment of coronary artery disease : Aspects on antithrombotic and percutaneous treatment options
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The outcome after percutaneous coronary intervention (PCI) has improved considerably thanks to more effective antithrombotic treatment strategies and improved coronary stents. Stent thrombosis (ST) is a rare complication to PCI associated with considerable mortality and morbidity.The general aim of this thesis was to add real-world evidence for antithrombotic and technical strategies in invasive treatment of coronary artery disease. Five observational studies were performed on a large, unselected, real-world population undergoing PCI. All studies were based on data from the national registry SWEDEHEART.In 31,258 patients undergoing PCI for ST-elevation myocardial infarction (STEMI), the rate of definite early ST was low (0.84%, n=265) but ST was associated with very high mortality (21%, n=51) at one year.Among 20,600 patients with STEMI, we compared the outcomes for those treated with heparin and those treated with bivalirudin during PCI. Rates of ST were low and similar with heparin and bivalirudin but all-cause mortality at 30 days and one year was significantly higher with heparin. We found no differences in rates of major bleeding, re-infarction and stroke.A novel bioresorbable scaffold (Absorb), used in patients undergoing PCI for all indications, was associated with a four- to eightfold higher adjusted rate of definite ST over two years, compared with conventional modern drug-eluting stents (DES). One in four ST events occurred later than one year after PCI. Rates of in-stent restenosis were comparable with Absorb and DES. Suboptimal implantation technique and non-adherence to antiplatelet therapy guidelines was common among patients with bioresorbable scaffold thrombosis.The novel parenteral and potent platelet inhibitor cangrelor was used nearly exclusively in STEMI (n=899), in early presenters with high-risk, often with cardiac arrest (18%) but was associated with low ST rates and no major bleeding events.In an unselected population of 65,000 patients undergoing PCI for all indications, the Xience permanent polymer everolimus eluting stent (n=36,600) appears to be safe and effective with low event rates of ST and in-stent restenosis. Compared with a control group of other modern DES (n=167,000) including a high proportion of thinner struts and absorbable polymers, Xience exhibits similar results in all important endpoints.All studies of this thesis provided important real-world evidence on antithrombotic and technical treatment strategies in invasive management of coronary artery disease.
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| 3. |
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| 4. |
- Kordestani, Arash
(författare)
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Incorporating sustainability in supplier relationship management : a study of Swedish manufacturing SMEs
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- "The future belongs to those who give the next generation reason for hope" (Pierre Teilhard de Chardin; 1881-1955). This hope may rely on sustainable development and sustainability of corporations. Corporations have found that one way to achieve sustainability is to establish it in cooperation with their suppliers. Existing research, however, offers limited insights into sustainable supply management and effective buyer-supplier cooperation.Based on the literature on purchasing sustainable responsibility (PSR), commitment-trust theory of relationship marketing, and the triple bottom line of sustainability as an interconnection among economic, environmental, and social issues, a conceptual framework has been developed. By adopting the concepts of PSR and buyer-supplier cooperation, this thesis proposes that buying firms can enhance sustainability performance of suppliers, thereby improving suppliers‘ adoption of environmentally and socially responsible capabilities. To explore this proposition, this study develops and tests a number of hypotheses concerning the direct relationships among PSR adoption, buyer-supplier relationship, and sustainability performance of suppliers. Also, a set of hypotheses regarding how a buyer‘s dependency on sustainable suppliers moderates their relationship has been developed so as to offer more precise insights to practitioners as well as scholars. In testing the study hypotheses, the researcher used both qualitative and quantitative approaches to develop the research instrument. The survey instrument captures the opinions and views of a sample of 400 Swedish purchasing professionals who have dealt with sustainable purchasing for at least one year. After data collection, a structural equation modeling approach was used to analyze the data and test the research hypotheses.The results concerning the direct-effect hypotheses indicate that the buyer-supplier relationship can be improved by adoption of sustainable purchasing. Also, buyer-supplier cooperation can improve the sustainability performance of suppliers. This thesis also shows that suppliers‘ adoption of PSR directly leads to improvements in their sustainability performance. Regarding the analyses of moderator effects, results indicate that some moderating effects exist. Findings indicate that the buyer shows lower levels of trust in, commitment to, and cooperation with suppliers in highly dependent situations.Overall, this thesis offers empirical results evidence that PSR is an effective approach to improve the buyer-supplier relationship and boost the sustainability performance of suppliers. The results of the direct and moderating-effect hypotheses lead to recommendations to buyers and suppliers regarding important factors to consider when making PSR adoption decisions.
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| 5. |
- Peighambari, Kaveh
(författare)
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Sustainable purchasing in the retail industry : a model of environmentally responsible purchasing
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Given the important role that businesses play in addressing the issue of environmental sustainability, a perspective on organizations’ responsiveness toward environmental sustainability suggests that one of the most challenging decisions to be made within an organization is to engage in environmental purchasing. Because preserving the environment and maintaining economic growth have become the goal for many organizations, decisions about sustainable organizational purchasing are growing in importance.Ethics research in business has tended to focus on a perspective of consumer environmental purchasing, leaving the understanding of the organizational perspective and why and how organizations purchase sustainably relatively under-researched. Among all the decisionmaking units, individual executives play a key role in sustainably responsible purchasing within a business. However, few previous studies have contributed to the role of the individual in such processes or examined the drivers and motives of environmentally responsible individual behavior in an organization. This thesis is a study under the rubric of understanding environmentally responsible purchasing behavior among purchasing professionals in the food retail industry of Sweden. Developed here is a theoretical framework that seeks an understanding of how environmental purchasing decisions are managed and affected by various factors in the organization. In other words, the research model of this thesis aims to investigate what determines purchasing professionals’ decision to engage in environmentally responsible purchasing. This is initially based on cognitive frameworks proposed by Fishbein and Ajzen’s theory of reasoned action, and ethical decision-making theories, but extended from findings of interviews with experts in the field and an in-depth review of the related literature. Based on the model, the factors of attitude, relativism, idealism, peers, and top management influence were proposed as possible drivers of environmentally responsible purchasing, considering stakeholder influence as a moderator in the framework. All of these relationships were empirically tested in response to the research question of this thesis. Using a quantitative research method, a survey was conducted to test this research model. This was to examine whether empirical results confirm this study’s hypotheses on the drivers of environmentally responsible purchasing at the individual level within the organization. A total of 573 usable questionnaires, providing a response rate of 37.4%, were tested using structural equation modeling (SEM) analysis to evaluate the proposed hypotheses on the research model. The results show how these factors influence environmentally responsible purchasing and provide support that all the proposed hypotheses are acceptable in the studied context.The acceptance of all proposed hypotheses highlights that moral beliefs and situational and organizational factors play an important role in an individual’s environmentally responsible decision–making process within an organization. The empirical findings also imply that the decision making in the context under study is far too complex to be explained only in terms of cognitive beliefs. The model offers insight into the drivers of attitudes and behavior in this context, positing a relationship between cognitive and emotional variables based on individual and situational aspects. In addition to theoretical insights, the findings of this study offer suggestions on how companies can effectively implement environmentally responsible purchasing by influencing their employees, yet fundamentally improve organizational culture.
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