Development of 4H-SiC Bipolar Devices
| Autor: | Chao, Li-Chiang, 趙力強 |
|---|---|
| Rok vydání: | 2014 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 102 The thesis reports the design and fabrication of 4H-SiC bipolar devices including p-i-n diodes and bipolar junction transistors. Conventional 4H-SiC p-i-n diodes suffers from a reliability problem called bipolar degradation. It is believed that the recombination of electrons and holes in forward conduction helps the expansion of stacking faults, resulting in an increase in forward voltage. In this study, p-i-n diodes were built on a thinned high-purity semi-insulating wafer with ion implantation to form P+ and N+ regions. At the same time, carbon implantation was implanted followed by a drive-in annealing to enhance the carrier lifetime. It is expected to solve the reliability problem.. Unfortunately, the experiment results are not as expected. The current density is only 0.0001 A/cm^2 when forward biased at 40 V. In bipolar junction transistors, by increasing the base doping, a smaller on-resistance at the cost of a reduced current gain is expected from simulation. Carbon implantation technique was also used in BJT fabrication to enhance the carrier lifetime. From experiments, however, the maximum current gain observed is only 2 with a large offset voltage of 0.4 V due to a high resistance from base to emitter. The effects of device geometry on the current gain were investigated. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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