| 1. |
- Lee, S. K., et al.
(author)
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Electrical characterization of TiC ohmic contacts to aluminum ion implanted 4H-silicon carbide
- 2000
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 77:10, s. 1478-1480
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Journal article (peer-reviewed)abstract
- We report on the investigation of epitaxial TiC ohmic contacts to Al ion implanted 4H-SiC. TiC ohmic contacts were formed by coevaporation of Ti and C-60 at low temperature (< 500 degrees C). A sacrificial silicon nitride (Si3N4) layer was deposited on the silicon carbide substrate prior to Al implantation in order to reach a high Al dopant concentration at the surface while maintaining a low dose. The combination of epitaxially grown TiC and the silicon nitride layer resulted in a promising scheme to make low resistivity ohmic contacts. The lowest contact resistivity (rho(C)) and sheet resistance (R-s) of the implanted layer at 25 degrees C were as low as 2 x 10(-5) Ohm cm(2) and 0.6 k Ohm/square, respectively.
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| 2. |
- Lee, S. K., et al.
(author)
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Low resistivity ohmic contacts on 4H-silicon carbide for high power and high temperature device applications
- 2002
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In: Microelectronic Engineering. - 0167-9317 .- 1873-5568. ; 60:1-2, s. 261-268
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Journal article (peer-reviewed)abstract
- We investigated titanium based ohmic contacts using co-evaporated epitaxial titanium carbide (TiC) on highly doped n(+)- and p(+)-type epilayers as well as Al ion implanted layers for high power and high temperature device application. Epitaxially grown TiC ohmic contacts on epilayers as well as Al implanted layers of 4H-SiC were formed by UHV co-evaporation with Ti and C-60 at low substrate temperature. The specific contact resistance (rho(C)) was as low as 5 x 10(-6), 2 x 10(-5), and 2 x 10(-5) Omegacm(2) for TiC contacts on n(+), on p(+) epilayer, and on Al implanted layer, respectively, using a linear TLM measurement. In addition to TiC, we also investigated TiW (weight ratio 30:70) ohmic contacts to p- and n-type 4H-SiC for the purpose of long-term reliability tests at high temperature. The average rho(C) of sputtered TiW contacts was 4 x 10(-5) for p(+) and n(+) epilayer. We also found that an evaporated top layer (Au or Pt) helps to protect from degradation of the contacts under long-term reliability tests with temperatures of up to 600degreesC in a vacuum chamber.
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| 3. |
- Lee, S. K., et al.
(author)
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Low resistivity ohmic titanium carbide contacts to n- and p-type 4H-silicon carbide
- 2000
-
In: Solid-State Electronics. - 0038-1101 .- 1879-2405. ; 44:7, s. 1179-1186
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Journal article (peer-reviewed)abstract
- Low resistivity Ohmic contacts of epitaxial titanium carbide to highly doped n- (1.3 x 10(19) cm(-3)) and p- (>10(20) cm(-3)) type epilayer on 4H-SiC were investigated. The titanium carbide contacts were epitaxially grown using coevaporation with an e-beam for Ti and a Knudsen cell for C-60 in a UHV system. A comparison of epitaxial evaporated Ti Ohmic contacts on p(+) epilayer of 4H-SiC is also given. The as-deposited TiC Ohmic contacts showed a good Ohmic behavior and the lowest contact resistivity (rho(C)) was 7.4 x 10(-7) Ohm cm(2) at 200 degrees C for n-type, and 1.1 x 10(-4) Ohm cm(2) at 25 degrees C for p-type contacts. Annealing at 950 degrees C did not improve the Ohmic contact to n-type 4H-SiC, but instead resulted in an increase in rho(C) to 4.01 x 10(-5) Ohm cm(2) at 25 degrees C. In contrast to n-type, after annealing at 950 degrees C the specific rho(C) for p-type SiC reached its lowest value of 1.9 x 10(-5) Ohm cm(2) at 300 degrees C. Our results indicate that co-evaporated TiC contacts to n- and p-type epilayers of 4H-SiC should not require a higher post-annealing temperature, contrary to earlier works. Material characteristics, utilizing X-ray diffraction, Low energy electron diffraction, Rutherford backscattering spectrometry, transmission electron microscopy, and X-ray photoelectron spectroscopy measurements are also discussed.
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| 4. |
- Lee, S. -K, et al.
(author)
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The formation and characterization of epitaxial titanium carbide contacts to 4H-SiC
- 2000
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In: Materials Research Society Symposium - Proceedings. - San Francisco, CA. ; , s. T691-T696
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Conference paper (peer-reviewed)abstract
- Epitaxial TiC Ohmic and Schottky contacts to 4H-SiC were formed by a new deposition method, UHV co-evaporation with Ti and C60, at low temperature (< 500°C). We achieved a contact resistivity of 2 × 10-5 Ωcm2 at 25°C for as deposited Ohmic contacts on Al ion implanted 4H-Silicon carbide. The rectifying behavior of TiC Schottky contacts was also investigated using I-V and C-V. The measured Schottky barrier height (SBH) was 1.26 eV for n-type and 1.65 eV for p-type 4H-SiC using C-V measurements for frequencies ranging from 1kHz to 1MHz. LEED, RBS, XPS, and XRD measurements were performed to analyze composition ratio, interface reaction, and structural properties of the TiC epitaxial layer.
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| 5. |
- Ovegård, Erik, et al.
(author)
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Operational Guidance with Respect to Pure Loss of Stability and Parametric Rolling
- 2012
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In: Proceedings of the 11<sup>th</sup> International Conference on the Stability of Ships and Ocean Vehicles (STAB2012).
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Conference paper (peer-reviewed)abstract
- This paper reviews two previously presented simplified methods for assessment of pure loss of stability and parametric rolling based on linear signal theory. The methods are evaluated in relation to full-scale incidents and time-domain simulations. Underlying assumptions and tuning of the critical levels in the simplified methods with reference to time-domain simulations is discussed. Given proper tuning the methods are concluded to provide a feasible basis for ship specific on-board operational guidance.
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| 6. |
- Rosén, Anders, et al.
(author)
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Experience from Parametric Rolling of Ships
- 2012
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In: Parametric Resonance in Dynamical Systems. - New York, NY : Springer. - 9781461410423 ; , s. 147-165
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Book chapter (peer-reviewed)abstract
- This chapter reviews three recent full-scale events with parametric rolling for Ro–Ro Large Car and Truck Carriers (LCTC). The events represent three principally different modes of parametric rolling: principal parametric resonance where the period of encounter is half of the roll natural period in following seas (I) and in head seas (II), and fundamental parametric resonance where the period of encounter coincides with the roll natural period in following seas (III). Roll motion, course, and speed recorded during the events are presented and analyzed together with the present weather situation based on recordings, forecasts, and re-analysis. Different aspects of on-board operational guidance for assisting crews in avoiding parametric rolling are discussed in relation to the presented events. Involved complexities and considerations that are normally not included in well defined model tests or numerical simulations are exposed.
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| 7. |
- Bhatt, Deepak L., et al.
(author)
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Rationale, design and baseline characteristics of the effect of ticagrelor on health outcomes in diabetes mellitus patients Intervention study
- 2019
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In: Clinical Cardiology. - : Wiley. - 0160-9289 .- 1932-8737. ; 42:5, s. 498-505
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Journal article (peer-reviewed)abstract
- In the setting of prior myocardial infarction, the oral antiplatelet ticagrelor added to aspirin reduced the risk of recurrent ischemic events, especially, in those with diabetes mellitus. Patients with stable coronary disease and diabetes are also at elevated risk and might benefit from dual antiplatelet therapy. The Effect of Ticagrelor on Health Outcomes in diabEtes Mellitus patients Intervention Study (THEMIS, NCT01991795) is a Phase 3b randomized, double-blinded, placebo-controlled trial of ticagrelor vs placebo, on top of low dose aspirin. Patients >= 50 years with type 2 diabetes receiving anti-diabetic medications for at least 6 months with stable coronary artery disease as determined by a history of previous percutaneous coronary intervention, bypass grafting, or angiographic stenosis of >= 50% of at least one coronary artery were enrolled. Patients with known prior myocardial infarction (MI) or stroke were excluded. The primary efficacy endpoint is a composite of cardiovascular death, myocardial infarction, or stroke. The primary safety endpoint is Thrombolysis in Myocardial Infarction major bleeding. A total of 19 220 patients worldwide have been randomized and at least 1385 adjudicated primary efficacy endpoint events are expected to be available for analysis, with an expected average follow-up of 40 months (maximum 58 months). Most of the exposure is on a 60 mg twice daily dose, as the dose was lowered from 90 mg twice daily partway into the study. The results may revise the boundaries of efficacy for dual antiplatelet therapy and whether it has a role outside acute coronary syndromes, prior myocardial infarction, or percutaneous coronary intervention.
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| 8. |
- Johansson, Jan-Olov, et al.
(author)
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Project: SATIN - System för användardriven tjänsteinnovation
- 2015
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Other publication (pop. science, debate, etc.)abstract
- The overall mission of SATIN is to empower end-users without programming skills to create mobile-services, and to share services with other end-users. In the project researchers from Luleå University of Technology and Umeå University join forces together with different industrial actors to solve the issues on technologies for mobile service-creation, user-driven service design and implementation and the future mobile service business ecosystem.
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| 9. |
- Palmquist, Samuel, et al.
(author)
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Market dynamics of buyout acquisitions in the renewable energy and cleantech sectors : An event study approach
- 2016
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In: Renewable & sustainable energy reviews. - : Elsevier BV. - 1364-0321 .- 1879-0690. ; 64, s. 271-278
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Research review (peer-reviewed)abstract
- This paper examined the market dynamics of mergers and acquisitions in the renewable energy and cleantech sectors. We analyzed abnormal returns from 273 announced and 54 completed buyout acquisitions that took place between the years 1997 and 2014, and we used an event study methodology to test (i) whether renewable energy and cleantech deals experienced higher rates of abnormal returns than traditional energy and mining deals, (ii) whether deal completions displayed similar effects as deal announcements, and (iii) whether homogenous deals experienced higher rates of abnormal returns than heterogeneous deals. Our findings were (i) that the traditional energy and mining sector outperformed the renewable energy and cleantech sectors in homogenous deals, (ii) that the deal completion effect followed the announcement effect in 9 of 12 cases, and (iii) that homogenous deals outperformed heterogeneous deals. To the best of our knowledge, comparisons of deal announcements and deal completion effects in the renewable energy and cleantech sectors have not to date been previously examined in the literature.
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| 10. |
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| 11. |
- Rosén, Anders, et al.
(author)
-
On the influence of sea state idealizations and wave directionality in dynamic stability assessments
- 2013
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In: Proceedings of the 13th International Ship Stability Workshop, Brest 23-26 September.
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Conference paper (other academic/artistic)abstract
- Simplified spectral based methods, concluded feasible for on-board analysis of dynamic stability limits in previous studies, are here adjusted for use in short crested seas and applied on a RORO ship using detailed forecast 2D wave spectra and corresponding idealized spectra. The general trend is that the idealized spectra result in over prediction of the probability of exceeding dynamic stability limits with a few exceptions resulting in under prediction. The results highlight the importance of proper representation of the wave environment in dynamic stability assessments. The results are discussed in the context of operational guidance and routing.
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| 12. |
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