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- Ghandi, Reza
(författare)
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Fabrication Technology for Efficient High Power Silicon Carbide Bipolar Junction Transistors
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The superior characteristics of Silicon Carbide as a wide band gap semiconductor have motivated many industrial and non-industrial research groups to consider SiC for the next generations of high power semiconductor devices. The SiC Bipolar Junction Transistor (BJT) is one candidate for high power applications due to its low on-state power loss and fast switching capability. However, to compete with other switching devices such as Field Effect Transistors (FETs) or IGBTs, it is necessary for a power SiC BJT to provide a high current gain to reduce the power required from the drive circuit. In this thesis implantation free 4H-SiC BJTs with linearly graded base layer have been demonstrated with common-emitter current gain of 50 and open-base breakdown voltage of 2700 V. Also an efficient junction termination extension (JTE) with 80% of theoretical parallel-plane breakdown voltage was analyzed by fabrication of high voltage PiN diodes to achieve an optimum dose of remaining JTE charge. Surface passivation of 4H-SiC BJT is an essential factor for efficient power BJTs. Therefore different passivation techniques were compared and showed that around 60% higher maximum current gain can be achieved by a newsurface passivation layer with low interface trap density that consists of PECVD oxide followed by post-deposition oxide anneal in N2O ambient. This surface passivation along with doublezone JTE were used for fabrication of high power BJTs that result in successful demonstration of 2800 V breakdown voltage for small area (0.3 × 0.3 mm) and large area (1.8 × 1.8 mm) BJTs with a maximum dc current gain of 55 and 52, respectively. The small area BJT showed RON = 4mΩcm2, while for the large are BJT RON = 6.8 mΩcm2. Finally, a Darlington transistor with a maximum current gain of 2900 at room temperature and 640 at 200 °C is reported. The high current gain of the Darlington transistor is achieved by optimum design for the ratio of the active area of the driver BJT to the output BJT.
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| 2. |
- Gölstam, Carl Martin, 1969-
(författare)
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Licensavtalet och konkurrensrätten
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The purpose of this thesis is to describe and analyse the significance of economic thinking and arguments in the treatment of licence agreements in EC competition law. A central question is to what degree the concept of competition in EC law reflects an economically realistic approach to competition. The study also investigates to what degree the economic functioning of intellectual property is considered in competition regulation and how much the economic functioning of the licence agreement is considered. The investigation mainly consists of a comparative analysis of EC competition law and American antitrust law concerning the economic arguments and their importance. The treatment of territorial restrictions, field of use restrictions, quantity clauses, tie-outs, tie-ins, grant back, no-challenge clauses and price restrictions are of special interest here. This study shows that an economically realistic view of competition has influenced current EC competition law, especially in the Technology Transfer Block Exemption Regulation (TTBER). Exceptions from this development in the EC law are mainly due to the goal of integration of the common market. Territorial restrictions are strictly regulated in the TTBER even when the parties’ market shares are below the market thresholds defined in the regulation.The function of intellectual property rights are not much considered in EC competition law but there are general remarks about the economic functioning of patents in the Guidelines for the TTBER. However, it is difficult to find evidence for economic reasoning about patents in the formation of concrete rules. On the contrary, patents are weakened by the widened concept of exhaustion presented in the Guidelines.The economic functioning of the licence agreement is considered in the rules of TTBER and the economic arguments for clauses which create incentives for making investments or give the possibility of control are acknowledged. However, the free riding argument has a weak position when applied to territorial restrictions, which are more formalistically regulated.The EC competition law has become more similar to American antitrust law. The decisive difference consists in the judicial treatment of territorial restrictions, where the goal of integration is still of central importance in EC law.
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